Making David and Goliath on Vimeo

<p><a href=”″>Making David and Goliath</a> from <a href=””>Octavio Aburto</a> on <a href=””>Vimeo</a&gt;.</p>

Rebreather Rules for Survival

In 2001, Andy Holman and I began a technical diving club in Southern California which did not go anywhere.  However, as part of our effort we compiled a few documents to help provide resources for the members and the general public.  I recently came across them.

This was produced to help rebreather divers in the group.  It is principally geared toward technical rebreather diving, but holds many very current points for recreational rebreather divers as well.

Not all components are current, deep stops are in question and there is growing evidence that some applications may no longer be best practice.

Would you add anything?  Remove anything?

There is a lot of common repetition between this document and the Open Circuit Rules as they are both meant to stand alone. Open Circuit Rules are here.

Rebreather Rules of Survival  (R2S)

  • 1.     Equipment

Maintain and prepare equipment a few days before dive day.

Leave unit on and gas on until on the boat and dekitting.

Don’t dive if equipment is not 100% working.

Don’t push limits of gas, absorbent, batteries, and your energy.

Be willing to ditch the dive or dive trip.

Take a spare OC rig, to switch over to, if in doubt.

Carry enough OC bailout to complete OC deco from furthest/worst point in the dive.

Do repeated FLAGS tests.

Ensure weight release configuration works.

Be willing to dump unit or gear to save your life.

Always conduct predive with a checklist in hand.

Always follow the checklist in a low stress and low distraction environment.

Always conduct a negative and a positive pressure check.

Never dive unless all three sensors are working.

Prebreathe the unit for confirmation of functionality.

Complete post dive checks with a checklist in hand.

Make sure you clean your rebreather properly each day.  Not all cleaners are created equal and many simply do not work.

Your rebreather is an extension of your own physiology, best to not put anything in your rebreather you would not want in you.

2.     Predive Planning

Make sure all variables are accounted for before entering the water. Complete accounting of oxygen, decompression, inert gasses, gas management, thermal exposure, mission, and logistics must be known for each diver in the team.

The following questions should be answered.


What is the planned PO2 for the dive?

What is the CNS and Pulmonary exposure?

Is there a better choice for set point?

Do I need to conduct a set point switch?

How do I plan to avoid Hyperoxia?

How do I plan to prevent Hypoxia?

What PO2 should I have in my diluent?

What PO2 should I have in my OC bailout?

Can you complete OC bailout with these PO2s?


What system will I use to safely control decompression on the dive? (EAD, Set Point Table, Air Computer, Nitrox Computer, Multi-gas computer, Constant PO2 computer, or Custom table)

What decompression obligation am I able to handle?

Am I qualified, willing, prepared, and able to do this level of decompression?

What will I do if the unit fails and I have to decompress on OC?

What contingency tables or backup do I use?

How do I plan on accomplishing decompression?

What method do I plan to use to communicate with the surface?

Where will I conduct decompression?

Inert Gasses:

Have I packed the canister properly?

Do I know exactly how much time I have on my absorbent already?

Has the absorbent settled after transport?

How much time do I have available for this dive with my absorbent?

Have I done anything that might cause absorbent channeling or failure?

Have I accounted for my CO2 production?

Have I accounted for temperature?

What level of narcosis have I planned for?

Am I comfortable with that level of narcosis?

Will I exceed crossover depth for my chosen PO2?

Is there a better choice for my diluent?

Gas Management:

Do I have enough oxygen to complete the dive?

Do I have enough diluent to complete the dive?

Have I accounted for the proper reserves?

Do I have the proper gas supply for OC bailout?

How will I inflate my drysuit?

How will I inflate my liftbag or SMB?


Am I properly insulated to complete the entire dive in relative comfort? (Losing heat can be as deadly as losing gas or not completing deco.)

Is a wetsuit proper for this exposure?

How will I supply gas to my drysuit?

Do I need argon?

How will I supply argon to my suit?

What is the bottom temperature?

What is the temperature I will be decompressing in?

Do I have the thermal tolerance to complete this dive?


Is this dive worth doing?

Should I be doing this dive?

What is the plan for the bottom?

Am I prepared for the bottom activity?

Do I have the necessary tools to be successful on the bottom?

Do I have the necessary skills and experience to do this dive with confidence?

Who is my team?

Am I comfortable with my team?

Does this dive require surface rehearsal?

Does this dive require dedicated surface support?

How am I being deployed on the dive?

How am I descending on the dive?

What is my priority list for the bottom?

What is my runtime for this dive?

When do I need to be off the bottom?

How am I ascending from the bottom?

How will I complete deco safely?

How will I communicate with the surface?

Do my support divers know how, when, and where to reach me?

Do I need to plan for any special procedures during deco?

How do I plan to handle gas switches if I make any?

How do I plan to communicate with my teammates?

How do I plan to deploy my liftbag or SMB?

Do I remember that deco is the longest part of the dive?

Do I remember that the dive is not over when I start deco and it is just beginning?

How will I handle OC bailout?

How do I plan to abort this dive?

How can this fail?


Do I have the absorbent I need to for all my diving?

Do I have all the gasses I need to do all my diving?

Do I have the platform necessary to be successful on this dive?

Do I have sufficient support for this dive?

Do I feel comfortable with everyone who will be on this dive?

3.     Drills while diving

Start of the dive, flush the unit with 100% 02 to validate PO2 readings and for surface activity.

Check all gas on, breathable mixture, unit on, mouthpiece in, exhale, then open before descending or entering the water on the unit.

Check the manual diluent add valve before descending.

Descend slowly.

Always do buddy check on the surface and a bubble check at 15ft.

Always know your PO2, Master every 2 minutes, Slave every 4 min.

Monitor primary and secondary displays.  You should always know your PO2.

Be aware of unexpected buoyancy changes or noise.

Use one breath in the bag constant volume monitoring.

Do a bailout drill at beginning and end of every dive.

At deco 15ft flush the unit with 100% 02 to validate PO2 readings and for surface activity. Ascend slowly.

Fully inflate BCD just before surfacing and opening loop.

Continue to breath 100% 02 while dekitting.

4.     Avoid Stress

Avoid rushing into water, rushing to put equipment on.

Time pressure will kill you!

There is always time for buddy check, bubble check.

Avoid equipment loading, buddy pressure.

Choose a patient Buddy.

5.     Are you solo diving

Watch your buddy to make sure your buddy is watching you.

Test your buddy (If you can count to 200 between buddy eye contacts your buddy will not save you).

Don’t solo dive.  Your qualified buddy is the last chance to save you.

If you solo dive be cautious, monitor PO2 more often.

The only time you and your buddy are safe is on the boat sitting down or on land out of the water.

Use constant and consistent communications throughout the dive.

Carry extra OC bailout.

There is no backup brain!

6.     Complacency

Watch for over confidence. Know your PO2 at all times.

If you are an expert technical diver, you are still a novice on a rebreather.  Do 100 dives above 100ft, before going deeper.

Workup to depth slowly from there, baby steps will save your life.

At the wrong time, the unit will bite you in the butt.  (Murphy’s/Sods Law)

Pyle’s Law:  at 50 hours you think you are hot stuff, at 100 hours you think you are there, at 150 hours you realize what a weenie you have been getting to 150 hours.

Other Rules

1. After you clear your 20-fsw stop (combining the 10-20 fsw stops for 1.6 PPO2) ascend at 1 fpm until you get to the surface.

2. Remove all gear and breathe while at the surface while still in the water…if possible for about 10 min.

3. Have a portable chamber on the boat if you are 220+ miles from land.

4. Don’t switch off Helium based mixes until 50-foot stop.

5. Have a back-up rebreather on the boat to allow surface support to replace a malfunctioning unit with the inflation of a specific colored lift bag.

6. Dives below 250 feet (75M) should not be conducted if unsupported.  If the exposures are long on shallower dives, they should be supported as well.

7. In open water operations, it is better to conduct multiple dives to depth rather than one long exposure.  The uncertain conditions in the ocean expose the diver to too much risks if decompression obligations are long.

8. Only you can control your dive.  The only mission that matters on any dive is that all return safely.  Nothing is worth dying for on a dive, including someone else.

Conclusion: OC is like a bicycle and CCR is like a helicopter both are transportation.  Bicycles work nearly all the time and its not a big problem if it does not, you walk.  You can abuse the bicycle and it keeps on working.  Helicopters you need to preflight test, watch the gas, watch gauges, be in control at all times, otherwise you will crash and die.  Riding a bike does not mean you can fly a helicopter…..

Open Circuit Rules for Technical Diving

In 2001 Andy Holman and I were working to launch a technical diving club in Southern California.  It did not really go anywhere.  But, part of our efforts was to come up with some resources to help members and the general public to be better divers.

I recently came across our efforts.  This was part of our work.  Most of it is still very valid. Some of the comments on deep stops may or may not be valid any more.  There is mounting evidence that certain applications of deep stops may not be best practice.

See what you think.  Anything you would add?

Anything that should be removed?

Rebreather Rules can be found here.

Open Circuit Rules of Survival  (OCRS)

Draft Version 1.2

1.      Equipment

Maintain and prepare equipment a few days before the dive day.

Don’t dive if equipment is not 100%.

Be willing to call the dive or dive trip.

Dive a standardize kit.

Ideally, the team should dive the same configuration.

Master one system for equipment first. Better to be good one way than crappy at a lot.

Equipment survey classes do not work.

Rig for wreck diving and dive with cave technique.

Learn how to adopt new configurations, if necessary.

Integrate configuration changes slowly.  Walk them up from the pool.

Use the most appropriate configuration for the planned mission of the dive.

Be multi-environment and multi-mode capable if your diving requires it.

NEVER dive a configuration without proper training in that configuration or mode or environment of diving.

Always plan for failure at worst point in the dive (depth, distance, time).

Be willing to call the dive at any point if safety is in question.

Always conduct predive checks.

Checklists are a good thing.

You should never dive if equipment is an issue.

Only use the best equipment possible.

Equipment should not be your limiting factor.

Carry only what is necessary for the dive and safety.

Streamline your kit for a balanced and hydrodynamic profile.

It is better to be good with your skills than to dive deep with bad skills.

Equipment handling and dive operations should be second nature.

Technical diving is more than equipment management.

Over-learn skills.  Responses should be automatic.

You should feel completely comfortable accomplishing something on the bottom phase of the dive.  If not, go back to the pool.

If you are amazed that you made it back from a dive, STOP technical diving.  Perhaps you should take up golf?

If you are not good with liftbags, learn how to use them.

Buoyancy control is critical for sport diving, I would bet it matters more here.

When diving wet, you must have a redundant BCD.

When diving dry, if you cannot swim without any air in your BCD at the beginning of a dive, your drysuit will not help you.  Have a redundant BCD.

Your kit should have sufficient redundancy to not have equipment keep you from coming back from a dive.  However, anything that is unnecessary should be removed.  Anything that is not standard must be justified.

All hoses are routed down and in.

One is none and two is one.

Always have a redundant gas supply.

If you are technical diving, doubles with an isolator manifold is mandatory.  Or use sidemount.

Independent doubles are unacceptable.

Always have enough gas to comfortably ascend while making all required safety and decompression stops.

2.       Predive Planning

Make sure all variables are accounted for before entering the water.

Complete accounting of oxygen, decompression, inert gasses, gas management, thermal exposure, mission and logistics must be known for each diver in the team.  If there is a number, you do not know for sure till you have one.

These are the planing questions that should be answered in each area.


What is the planned maximum PO2 for the dive?

What is the CNS and Pulmonary exposure?

Is there a better choice for maximum PO2?

What is the maximum PO2 that is acceptable for decompression?

How do I plan to avoid Hyperoxia?

How do I plan to prevent Hypoxia?

Do you have enough room in CNS time to extend the profile?

Have I accounted for repetitive dives and/or repetitive days?

Have I visualized my gas switches?

Do I have a system for gas switching?

Are my cylinders properly marked?

Are my cylinders analyzed?

Do I have a system to cover a bad gas switch?

Do I carry my deco gas with me or can I stage it?

What schedule do I plan for oxygen breaks?

Is this schedule often enough? Or too often?

Do I plan on making back gas breaks before a gas switch?


What system will I use to safely control decompression on the dive? (EAD, Air Computer, Nitrox Computer, Multi-gas computer, or Custom table)

What decompression obligation am I able to handle?

Am I qualified, willing, prepared, and able to do this level of decompression?

What if I over stay my bottom time?

What if I exceed my planned depth?

What contingency tables or backup do I use?

How do I plan on accomplishing decompression?

What method do I plan to use to communicate with the surface?

Where will I conduct decompression?

Have I properly padded my deep stops?

What if I have to bailout from the dive early?

Am I accelerating my deco?

What if I get bent?

Do I have sufficient oxygen for the dive and post dive?

Can I perform surface decompression?

What rate do I plan to ascend during the dive?

Can I slow down my ascent to the surface?

Can I rest at the surface?

Can I remain on oxygen at the surface?

Are my buoyancy skills good enough to conduct deco in blue water with no reference?

What algorithm do I plan to use for calculating the dive profile?

Is everyone comfortable with the profile?

How will I handle the loss of a deco gas?

How will I abort the dive early?

Can this be made easier?

Inert Gasses:

What level of narcosis have I planned for?

Am I comfortable with that level of narcosis?

Am I considering oxygen as narcotic?

Have I accounted for my CO2 production?

How do I plan to minimize CO2 issues?

Are there mission considerations that would require a different choice of gas in regard to narcosis?

Am I diving in an overhead (wreck, cave, or ice) environment?

Am I accustomed to this environment?

Is it darker, deeper, or scarier than I have experienced?

Gas Management:

Do I have enough oxygen to complete the dive?

Have I accounted for the proper reserves?

Do I have enough back gas?

Are my gas choices the best for the mission?

What intermediate gasses do I want?

Can I carry all the gas I need with proper reserves?

Should I shorten the dive to allow for more reserve?

Can I maintain the breathing parameter necessary to conduct this dive as planned?

Do I really understand that gas is time at depth?

Do I have sufficient gas if I exceed my depth or over stay my planned time?

Do I need dedicated support?

How will I inflate my drysuit?

What is my gas management plan and is it appropriate?


 Am I properly insulated to complete the entire dive in relative comfort? (Losing heat can be as deadly as losing gas or not completing deco.)

Is a wetsuit proper for this exposure?

How will I supply gas to my drysuit?

Do I need argon?

How will I supply argon to my suit?

What is the bottom temperature?

What is the temperature I will be decompressing in?

Do I have the thermal tolerance to complete this dive?

Have I planned for repetitive dives?

How will I rewarm after the dive?

Will I continue to lose heat after the dive?

Is there a better choice for insulation?

Should I shorten the dive to account for heat loss?

Have I dived in this temperature before?

Do I remember that the water is always colder than I think?


Is this dive worth doing?

Should I be doing this dive?

What is the plan for the bottom?

Am I prepared for the bottom activity?

Do I have the necessary tools to be successful on the bottom?

Do I have the necessary skills and experience to do this dive with confidence?

Who is my team?

Am I comfortable with my team?

Does this dive require surface rehearsal?

Does this dive require dedicated surface support?

How am I being deployed on the dive?

How am I descending on the dive?

What is my priority list for the bottom?

What is my runtime for this dive?

When do I need to be off the bottom?

How am I ascending from the bottom?

How will I complete deco safely?

How will I communicate with the surface?

Do my support divers know how, when, and where to reach me?

Do I need to plan for any special procedures during deco?

How do I plan to handle gas switches?

How do I plan to communicate with my teammates?

Do I remember that deco is the longest part of the dive?

Do I remember that the dive is not over when I start deco and it is just beginning?

How will I handle the loss of a gas?

How do I plan to abort this dive?

How can this fail?


Do I have the resources to do this dive?

Do I have all the gasses I need to do all my diving?

Do I have the platform necessary to be successful on this dive?

Do I have sufficient support for this dive?

Do I feel comfortable with everyone who will be on this dive?

Do I have all the components necessary to conduct all the diving for all the days planned?

3.       Drills while diving

Conduct gas, depth, and time checks on all dives.

Always check lights, leaks, thirds, and valves on the surface.

Always conduct an S drill when diving with a new partner.

Always conduct a modified S drill on all dives.

Ensure that you are able to maintain depth at the end of the dive with minimal gas and no stages or with stages if stages are buoyant.

Be aware of unexpected buoyancy changes or noise.

Practice valve shut downs often.

Valves all open on back gas.  Stages are charged and off.

When conducting gas switches, always purge the second stage prior to attempting to breathe from it.

Always use anti-silting techniques.

Maintain a balanced and hydrodynamic profile at all times.

Communicate with your partner at all standardized times and as needed.

Remember your role as a backup brain.  Do not let yours go on vacation.

Anyone can call any dive for any reason with zero consequences.

4.       Avoid Stress

Avoid rushing into the water or rushing to put equipment on.

Time pressure will kill you!

There is always time for a buddy check, bubble check.

Avoid equipment loading, buddy pressure.

Choose a patient buddy.

5.       Are you solo diving?

Watch your buddy to make sure your buddy is watching you.

Test your buddy (If you can count to 200 between buddy eye contacts your buddy will not save you).

Don’t solo dive.  Your qualified buddy is the last chance to save you.

If you solo dive, be cautious, dive shallower than usual for less time and under more ideal conditions.

The only time you and your buddy are safe is on the boat sitting down or on land out of the water.

Use constant and consistent communications throughout the dive.

Carry extra gas.  Gas is time underwater.

If you run out of gas and it is not due to equipment failure, IT SUCKS TO BE YOU!  Your buddy’s reserve is not for you.  It is his.  He can choose to give it to you, but it is not yours’. Do not treat it like it is, plan accordingly.

There is no backup brain!

6.       Complacency

Watch for over confidence. Are you really ready for the dive?

There are old tech divers and there are bold tech divers.  There are very few old and bold tech divers.

Work up to depth slowly; baby steps will save your life.

Never let your brain talk your ass into something it cannot get you out of.

If you suck, you should know it at this level.  Get better training.

Keep training until you are totally confident in your skills.

You are never totally confident in your skills.

You are never done.  Get over it already.

You are not as good as you think you are.  No one is.

Progressive penetration is bullshit.

Other Rules

  1. After you clear your 15-fsw stop ascend slowly to the surface.  The dive is not over till over a half an hour has gone by on the surface.
  2. After you clear your 15-fsw stop ascend slowly to the surface.  The dive is not over till over a half an hour has gone by on the surface.
  3. Breathe oxygen at the surface with minimal movement for at least ten minutes after a dive, if possible.
  4. Have a portable chamber on the boat if you are 220+ miles from shore.
  5. Think carefully about when and how you switch off helium mixtures.  It might be better to keep some helium in your mixes until on oxygen.  Oxygen is your friend.
  6. Always analyze all of your gasses immediately before diving.  Label them appropriately.  Never breathe any gas unless you are absolutely certain what it is.  Have a system for gas switches, visualize them, and double check your buddy after every switch.  Monitor yourself and your buddy for signs of hyperoxia.
  7. Have necessary backups on the boat with you.  Support divers should be able to solve most problems.  Make sure your plans deal with proper logistics for support divers if they are needed.  There are no dive shops at sea.
  8. Dives below 250 feet (75M) should not be conducted if unsupported.  If the exposures are long on shallower dives, they should be supported as well.
  9. In open water operations, it is better to conduct multiple dives to depth rather than one long exposure.  The uncertain conditions in the ocean expose the diver to too much risk if decompression obligations are long.
  10. Only you can control your dive.  The only mission that matters on any dive is that all return safely.  Nothing is worth dying for on a dive, including someone else.
  11. If you are going to pad your decompression do it deep, the benefits out weigh padding stops in shallow water.  Skew decompression to deeper stops.  Be slow to get off the bottom; do not rush to get shallow.  Plan accordingly.  Deep stops are more important than shallow stops.  All stops are important.
  12. Plan the dive and actually dive the plan.  The devil is in the details. Execution is more important than accomplishment.  It is not what you do, but how well you do it.
  13. Utilize precision diving techniques and skills.  Always try to be better tomorrow than you were today, better the next dive than this one, and better on this dive than the last one.
  14. Strive to know every aspect of any dive you go on.  If there is a number, have it.  If there is a concern, answer it.  If there is a doubt, don’t dive with it.  Know where you are and all aspects of the dive at all time.  Develop super awareness to all components and activities of the dive.  You will see things before they are issues and take steps to fix them before you would have even noticed them in the past.

Conclusion: If you cannot or will not accept the risks, costs, physical demands, training requirements, and/or mental demands that technical diving requires, you should not attempt it.  There are plenty of great adventures to be had in shallow waters.  Just diving deep or going into required stops on your computer is not technical diving.  It is just stupid.  Technical diving is an adoption of a mindset, approach, and attitude as much as it is diving with the gear or taking training.  If you choose to do this, do it well.  Keep training and never dive unless you know you will be successful.  Your life is always the most important one.

Rebreather Forum 3.0

Rebreather Forum 3.0 brought together the leaders and shakers in the rebreather world May 18 – 20, 2012.  The event took place in Orlando, Florida at the Caribe Royale Hotel Convention Center.  Participants from around the world gathered to listen to and participate in presentations in three areas of concentration, incidents, design and testing, and operations and training.  The event had over 400 attendees.

The last rebreather forum occurred in 1996 in California.  The sixteen years that have passed since that event have brought with it many substantive changes within the industry.  This meeting would challenge old thinking and consider if the foundational questions had changed much at all.

The forum’s objectives were stated as follows,  (

“To establish the state of the art of rebreather diving, and where appropriate, to make recommendations in the following areas:

  • To codify the state of the art of rebreather use, including issues such as ventilatory characteristics, oxygen control, CO2 control, automation, warnings, bail-out system, redundancy and backup systems.
  • To review available data for accident analysis and avoidance.
  • To review training and operational protocols.
  • To examine considerations for conducting extreme exposure dives.”

The event was made up of a preamble Explorer Day followed by two and half days of forum events.  The Explorer Day allowed participants to “try dive” units of their choice in the hotel pool.  AP Valves, Revo, Titan, Inner Space, and several other manufacturers participated in the demos.  The presentations were broken into three concurrent tracks with various talks of a half hour to one hour in length.  These tracks focused on general rebreather topics, rebreather medicine and physiology, and rebreather business and operations.   There was a ready supply of enthusiastic newcomers to rebreathers with many demo participants having never tried a rebreather before.

All of the presentations were standing room only with some stretched for space.  Notable speakers like Richard Pyle spoke on his diving with rebreathers and the evolution he has seen since the last rebreather forum.  Dr. Simon Mitchell presented on CCR Physiology.  Jill Heinerth put forward her Five Golden Rules for rebreather diving.  Richie Kohler talked about the importance of checklists.  James Morgan showed why he stopped blowing bubbles, well sometimes stops blowing bubbles.   Evan Kovacs got the audience very close to the action of his film subjects with the help of rebreathers.  One big surprise was when training agencies TDI, IANTD and ANDI shared their certification data regarding rebreathers in an open session planting the seed for open sharing in the future with all agencies.

Jill said, “RB3.0 was the most important gathering of technical divers that I have ever attended. The rebreather community has finally reached critical mass, allowing participants to express their opinions and move the industry forward in safety and transparency in a way we have not seen before.”

The forum program proceeded in the evening after the Explorer Day.  The forum format changed to a single track of presentations in the large ballroom.  Dr. Drew Richardson opened the forum.  Michael Menduno provided a retrospective of what has been learned from Rebreather Forum 2 with many of the players from that event present at the current event.  Dr. Richard “Harry” Harris led us through his inspiring deep work in New Zealand and Australian caves with an emphasis in overcoming obstacles in exploration.  The evening wrapped up with a panel on different user groups within the rebreather community.  In a stark contrast to previous events, the US Navy openly shared their user data and incident rates.

Supervisor of US Navy Diving, Commander Runkle, presented diving statistics for the 2011 year of diving.  The US Navy conducted 105,463 dives with a total of 5,503,406 minutes of Total Bottom Time.  Twenty-six incidences were reported.  Forty-four percent were related to rebreathers with the remainder being related to open circuit scuba and chamber operations.

During the previous five years the majority of incidents with navel rebreather use were related to lung trauma with forty-one percent attributed to air gas embolism.  Most of these related to the use of oxygen rebreathers.  This is the first time the navy has been so open with their data.  This should allow researchers to begin to establish a denominator related to rebreather use and incidences in at least this population of users.

Day two

A focus on incidents brought the morning to a humbling beginning.  Chaired by Dr. Petar Denoble, DAN’s incident guru, the sessions were focused on what the origins and results of fatalities and near miss incidents have been thus far.  Dr. Andrew Fock gave an overview of CCR Diving Fatalities and review of known events.  Lawyer David Concannon spoke to the legal cases that have arisen from incidents.  He reviewed cases he has defended and spoke to the need to pay more attention to triggering events that lead to fatalities rather than just the end result of the fatality.

Dr. Bill Stone spoke to the hazard analysis and human factors he investigated in the original development of the Cis Lunar and the continued efforts he has conducted with the Mk 6 and Poseidon’s new tech rig.  He began his presentation with the announcement of a landmark agreement between Poseidon and DAN to house all Mk 6 data that they have and into the future.  He then introduced his topic by saying; “We are leaving the cowboy era in rebreathers.”

Bill approaches rebreathers with the same mindset as he does when working on projects with NASA.  His analysis compared failure modes for open circuit to closed circuit.  The development of machines that can recognize and deal with variable environments and problem solves was illustrated by his footage of the self-driving car work he conducted with NASA.  Putting the Google car to shame, this vehicle can drive itself and recognize appropriate paths off road.  Many of these projects have lent ideas and technologies for the “smart systems” being incorporated into today’s rebreathers.  This is one of the big changes since the last forum.

This wrapped up the segment on incidents.  What was clear from the morning was that there can be advances in technologies and smart systems, but engineering will not remove the diver from the system.  Recreational diving will always be diver dependent.  You cannot engineer the diver out of the system.  So, there is also a need to focus on fixing the diver on all levels.  This places a high standard on training and community development.  If the user base is going to grow quickly a focus on this will be more necessary than ever before.

Focus Zone 2 revolved around design and testing.  Chaired by NEDU’s Dr. John Clarke, this focus area occupied the majority of the event.  Martin Parker of AP Values spoke about real time monitoring.  The talk was highlighted by a discussion of the systems they incorporated into James Cameron’s Deep Explorer sub for his successful dive to the deepest depths of the ocean.

Dr. Arne Sieber presented on oxygen sensor technologies.  Current sensor technologies have not changed much for a long time.  There are pressures to change sensors to comply with environmental laws that may make them incompatible with rebreather use.  This is scary news for rebreather divers.  The good news is that new technologies are being developed that could be available soon.  Data was presented that sensors are much more temperature sensitive than most would believe.  So, special care should be used when dealing with lower temperature environments.  Also, real time in mouthpiece oxygen and carbon dioxide monitoring has been beta tested.  Not ready for inclusion in production units yet, it speaks to a bright near future for improving this vulnerable area of the technology.

Kevin Gurr reported on online research he conducted into rebreather diver behaviors.  Results were self-reported by rebreather divers.  Scary data resulted.  A large number of divers were ignorant to the units they were diving and owned.  Simple capabilities and confusion about durations and depth limits were clear.  Sixty-four percent of those that self reported symptoms of carbon dioxide issues did not bailout nor did they end the dive.  The second half of his presentation focused on carbon dioxide sensors.  He believes we are four to five years away from real time in mouthpiece monitoring on production units.

Dr. Dan Warkander of the US Navy’s Experimental Diving Unit (NEDU) talked about carbon dioxide scrubber technology.  Dan spoke to the need for clear understanding of scrubber capabilities for temperature, workload, and depth with more available information from manufacturers to help divers make intelligent decisions about duration.   He presented data from navy tests that illustrate that canister durations can vary as much as five to twenty times based on temperature, depth, and workload.  Pointing to the importance to know the numbers for the unit being dived and the conditions it is being dived in.

Bruce Partridge of Shearwater fame finished up the day presenting on information technologies and the incorporation of real time data tracking into rebreather systems.  Bruce illustrated that no IT solution or mitigation designed into a rebreather can replace the need for checklists.  He did a wonderful job looking at how other industries have dealt with risk and how it was mitigated.   It is clear that a lot more data tracking is in the future.

The evening concluded with a gala dinner.  The keynote speaker was Dr. Michael Gernhardt, a NASA astronaut and diver, talked about exploration from sea to space and back.  The primary focus of his work has been on decompression modeling and space suit design.  More recently he has been working on the mission to mars and the more recent focus on near asteroid exploration.  Video of the mission testing brought the technology to life.  The presentation was a fascinating look at the future of space exploration with exciting possibilities of spin off benefits for rebreathers in the future.

Day 3

Dr. John Clarke continued chairing his focus area on testing.  Dr. Nigel Jones spoke about oxygen control.  Gavin Anthony and Mike Ward talked about pre-market testing.  Third party testing of units is the only way to verify the data provided is unbiased and can be trustworthy.  It is required of CE compliant units and the standard by which most have relied for decades.  Luckily, it is far more common today than at the time of the last forum.

Vince Ferris of NEDU and Oskar Franberg of Sweden presented on post incident testing of rebreathers.  The need for resources for analysis of rebreathers after an incident is clear.  Both of these gentlemen do this for their respective navies.  Civilian resources are limited and there is a clear need for resources to assist when there is an incident.

Dr. John Clarke closed the focus session with his favorite topic, semi closed rebreathers.  He playfully pointed out that the ultimate rebreather is the earth.  His work at the NEDU has allowed John to see and experiment with so many units and technologies that it is remarkable how broad his knowledge spans.  He pointed to some of the newer technologies possibly making semi closed rebreathers an option in the sport market.

After lunch focus zone 3 began concentrating on operations and training.  Phil Short chaired the session.  First up was a panel chaired by Dr. Jeff Bozanic on operations.  Dr. Richard Pyle discussed the history of his “twilight zone” fish collecting in the mesophotoic region.  He has a return on time of twelve new species of fish for every hour of bottom time.  He has also seen that for these deep technical dives open circuit requires over twice the hours of support than that of closed circuit.

US Park Service has found that rebreathers have increase work productivity by thirty-two percent over open circuit.  Most of the work being done is in the fifty to one hundred feet ranges.

An entertaining segment of the panel was a presentation on opinion versus science.  Those on the inside of rebreather understand well that opinion and science can be tough to distinguish when it comes to this topic.  The question still remains; will opinion or science dictate policies for rebreathers in the future?

Jill Jeinerth and Terrence Tysall chaired the final presentation focused on training.  Rather than having a traditional panel they decided to have a series of questions with audience participation to help answer them.  The majority of time was spent on the question of how to encourage or drive the use of checklists.  The root of the discussion was how to drive community behavior and move away from complacency.  A difficult question under any circumstances with the hopes of massive increases in users the timing is critical to address the issue.

How can you drive change in cultural bias when that bias is not good for diver outcomes?  Some hopes were presented for engineering that would require the behavior or not allow diving.  Some pointed to increased strictness in training requirements.  But, in the end, there is nothing that can make a diver not be complacent.  Attitude can be modeled, but not trained.

So, although these solutions can contribute to a new cultural bias, they cannot make it happen.  The diver cannot be engineered out of the equation.  A paradigm shift is required of all existing rebreather divers.  Speaking up when behaviors are witnessed that clearly deviate from safe practices needs to be standard operating procedure.  Terrence rightfully pointed out that we can go to a system based operation, but that is not going to be very pleasant for those that want to be able to dive without controls and support staff.

So, how do you shift to a new “good” cultural bias?  It is a difficult question and there is no easy answer.  Jill believes that checklist use needs to become the cool thing to do.  She believes that the role models in the sport need to drive that effort.  In some ways the changes in behavior can be easy, if it is established in the new users if that new user group explodes in number of users.  Much like a generational shift, not many remember not having CDs and many younger people have no concept of music being anything but a digital file.  The problem is if it does not change for them, then you are left trying to correct behavior already established in a much larger group of users than before.  So, the time is critical for this effort.

There was an assumption that training is taken care of by the audience, that there is little work to be done there.  In the last Forum, it was a critical question.  Advances in rebreather design may make the challenges easier to deal with, but the glaring lack of questions regarding the area of training should be considered when looking forward.

Is it safe to assume that training is adequate and not deserving of close evaluation?  Does the condition of training currently available in the industry warrant this belief?  Even with new developments, is training covering the necessary topics and providing the discipline and skills necessary no matter what the engineering requires of the diver?  Is instructor quality still or even more bound to good student outcomes than before?  Can a massive increase in users be safely handled if the instructor still matters far more than the program being used to train the diver with?  What should be done about it if this is all true?

Dr. Simon Mitchell moderated the closing session that reviewed the key points of the Forum.  Consensus recommendations were presented and voted on.  Not an easy task.  However, the work was far less conflicted than at the last Forum.  These recommendations are available on the Rubicon Foundation site.

Drew Richardson summed up the event, “After over 2 years of planning, RB 3 was a tremendous success and a worthwhile build on the previous Forum. The industry grows together when we work together and this is an example. The findings and interactions at this safety conference will help us move forward with closed circuit technology in a responsible manner”

Michael Menduno, the organizer of the first two rebreather forums, said, “I believe that rebreather technology is at another inflection point in its development. The first coincided with the emergence of technical diving—what you might call the “mix revolution,” which represented necessary infrastructure for the development of rebreathers. At that point, rebreathers like Bill Stone’s Cis-Lunar Mk-1 were just a tech diver’s dream. The second inflection point was in the mid-90s, with the emergence of the first sport diving rebreathers like Ambient Pressure’s Inspiration and the Dräger Atlantis.

Today, rebreathers are moving out of the “test pilot” era to become a true consumer product (think Poseidon’s Mk-VI or the Hollis Explorer). Granted, this transition will take time. Ten years from now, fifteen years from now, I suspect people will look back on today’s technology, and say “Geez, you actually dived those units without knowing exactly what you were breathing? OMG!” It’ll be like us looking at early cave divers using J-values and empty Clorox bottles for buoyancy, and going, Really?”


I was recently asked to speak at the Adventurers’ Club of Los Angeles about adventure.  I had visited the club several months before after being asked to speak.  Between my visit and my scheduled night to speak I had a lot of time to think about what I would say.  The earlier visit with this interesting group brought something to my attention that I had not thought about much.  Do you need a reason to justify adventure?  Do you need to have a justification for being adventurous or pursuing adventure beyond the adventure itself?

Over the last decade, I have noticed a trend toward a feeling from adventurers that they need other reasons for pursuing what they do.  The press, public, funding institutions, and even the explorers themselves seem to have a growing pressure and feeling that there needs to be additional reasons for pursuing adventure or setting out on expedition.  There needs to be some scientific angle or educational component or media tie in or all of the these and more.  If not, somehow the effort is less valid.

I asked the assembled group at the Adventurers’ Club this question.  Does there need to be a reason?  Their answer was because it is there.  A rather famous line from a more than famous explorer.  But, it is not an answer that seems to meet the current expectation of the public and the press or even most explorers.

I think this creates a problem.  It implies that somehow adventure is not valid or somehow a selfish act if it is not connected to something outside of the adventurer.

When did adventure for adventure sake lose its luster and it validity?

There was a time when it was considered a high pursuit.  In fact, for most of our history because it was there was the primary reason for adventure.  In some ways this has almost become a dirty word.  The sad thing is that it also changes the mindset of all of us about adventure.  That somehow you have to be involved in a big effort with funding and production crew attached to participate in adventure.  It takes adventure out of the hands of each of us and into the hands of an exclusive few.  It leads us to believe that adventure is only in the biggest of expeditions or projects.

Adventure never changed, it is our perception of it that has.  Adventure is everywhere and can be in the smallest of events.  Even in a moment.  Adventure is a very personal thing.  The biggest part of any adventure is where we travel in ourselves and the way that experience transforms us.  There is no event that is not worthy of being called an adventure.  It is up to the individual to decide if they have had one or not and to pay attention and experience it.

More importantly, if we allow adventure to escape our personal experiences and become the exclusive domain of big well funded projects and expeditions only seen on television, we believe we cannot have adventure in the most simple of moments.  Adventure can be big or small, just as the transformations that come from them.  Even worse, if we allow ourselves to believe that adventure is not everywhere, we forget to pay attention and look for it in what we consider the mundane.

Going to the market can be an adventure.  Not all adventures are necessarily good ones. LOL  But, seriously, if we forget we all can be adventurers, we live a less fulfilling life.  Adventure is a choice and about making a choice to go or do something unexpected or outside our normal choices.  It is about opening our eyes and noticing things we normally do not pay attention to.  Or just choosing to go somewhere we have not been before, perhaps without a plan or reservations to do so.  Or perhaps just within ourselves.

In the age of viral media and 100 plus channel choices have we forgotten that adventure is personal?  That each of us has the ability to have adventure in the smallest of experiences?  Sadly, most that appear to pursue adventure for adventure sake become labeled as adrenaline junkies or thrill seekers.  So, those that come to adventure differently feel they need the additional justifications to separate their efforts from the adrenaline junkie.  It leads to a situation where the pursuit of adventure can feel selfish or self indulgent and be viewed that way by the public.

We lose a lot if we allow this to continue to progress.  Because it is there or because I can is fine if there needs to be a reason at all.  Not all choices will be good ones, but that is up to each individual to decide.

Think how much we would have lost from history if those that decided to do differently thought it was a selfish pursuit or that it was unaccessible to the individual?

More importantly, we forget.  We forget that each of us is a choice away from adventure.  It can be as simple as paying attention and noticing something you pass everyday, differently.  Or exploring a thought  or idea we allowed no space for years.  Or driving in a different direction to work.  Or participating in a larger project or expedition when we believed that to be impossible.  Or simply taking the time to go somewhere and not have plans.

I did not know what I wanted to talk about for the club.  I decided I would speak to adventure in the context of my life.  Developing the talk, I realized I was an adventurer and most of the time I had not initiated the adventure but was an accidental tourist for many adventures.  That adventure is not just a function of the massive expedition or project, but also lives in the simplest of choices.  Most importantly, that I do not need to feel the need to layer on other reasons for pursuing adventure unless I desire it.

Adventure for adventure sake is a noble pursuit in and of itself.


I call it this because the final two foundational skills are related to movement.  Breathing and buoyancy are in play at all times when we dive.  If we are stationary, these two pillars of Precision Diving have the largest impact.  Diving being active, we do not sit still all that often and when we do it tends to be for short periods.

The final two pillars of Precision Diving are all about movement.  This is why I present them together.  Swimming and trim are the cornerstones of our movement as divers.  Swimming is how we actually create the movement.  Trim is how we control how the water moves past us.  Or how we move the water out of the way when we move through it.  Of course, breathing and buoyancy need to be ideal and are in play as well.  But, the choices we make in how we move, position ourselves, and configure our gear has big impacts on our performance while we dive.

Most divers learn to flutter kick.  There is nothing wrong with that.  I do wonder why it stops there with most new divers.  There is nothing preventing an instructor from working on more than one way to use the fins.  Well, perhaps motivation and a bit more time.  But, if you are a new diver or about to become one, demand to learn more than one way to kick/propel yourself.  It is important and it will serve you well to learn this early and have the choices be automated early for you.

Precision Diving is not about one type of gear or one style of anything.  This holds true for fins.  A good diver should be able to use any fin.  The choice of what is good is a very individual thing and should be done through trying many out and then making the choice for which fin best suits your needs and diving.  You may find that you choose more than one pair of fins for different activities.

I use different fins for daily diving then I do for cave diving.  I use another type of fins when I freedive and even sometimes use a monofin.  So, select fins that work best for the performance you need out of that tool when and where you need it.

Of course, when you are new, you need to start with something.  So, this is where is pays to have a good relationship with your instructor.  Make sure you have a good conversation about what type of diving you plan on doing and where you plan to dive.  Once your instructor fully understands your needs, then you can consider their recommendation.

Fins are important.  They are the engines by which we create our movement underwater.  Invest in something good.  Fins tend to last a very long time and most people do not buy new ones because they wear their fins out.  Usually new fins are purchased because there is a new feature someone wants.  It is important to make sure the fins suit you and your diving.  In spite of what some say, no one pair of fins works for everyone in all applications.  Those that disagree, I am very happy that you have found something that works so well for you personally.  However, this is not true for all.

A fin that is too stiff can cost you more energy and create more work for you if you are not prepared to use them.  This will take bottom time away and you will consume more breathing gas.  This is not optimized performance and not Precision Diving.

Some fins may be too negatively buoyant for your body composition.  This will cause your feet to sink and you will need to make other compensations to counteract that shift in buoyancy.  This is possible to accomplish, but at what cost?  It might be simpler and better just to consider another fin.  One that is less negative.  Perhaps simply made of another material in the same style you like.

The same holds true if your feet tend to float. A more negatively buoyant fin may be the best solution rather than adding ankle weights or making some other compensation. Make sure if you do adjust for floating feet, that you do not go too far the other direction causing you to have to fight negative buoyancy in your feet now.

It is important to consider the kicking style and learn the correct one for the fin you use.  This means it would be wise if you change fin style and that new fin requires a different technique that you request some time with an instructor comfortable in tutoring you in the finer points of this new technique.  At least get good input on what those differences in technique are.

Split fins are very different from straight bladed fins.  Other fins have very unique kick styles needed to optimize their performance.  It is important to understand what your fins require.  If you go on to use more than one style of fin, you will need to make sure you master each style’s required techniques and also create a ritual around each fins’ use to help you be able to seamlessly move from one to the other with minimal workup in between.

Just as we do not assume that breathing is something we know how to do as Precision Divers.  We do not want to assume that we should “just know” how to optimize performance in any fin.  I hear it all the time, “It is just fins.”  Um, no it is not.  Most divers that began with straight bladed fins who switch to split fins tend over kick them with far too great a length of kick.  This only blows water through the split defeating the purpose of the design.  Similar issues are faced by those making the switch the other way with under kicking.  Other designs can be equally difficult.

Fins are the engines of our diving.  So, make sure you understand how to get the best performance from your engine before you assume you “just know”.  We generally do not jump into a car we have never driven without first “figuring out where everything is”.  Make sure you do the same with your fins.  If you get resistance from your instructor about a demand to work on use of fins, then find a new instructor.  Same for a retailer.  If the shop you use does not want to help you learn how to better use the gear they sold you, then it is likely time to find one that will.  They should charge you for this service as well.  You want to make sure that the service is provided fully and not blown off.  Pay peanuts, you get monkeys.

Most shops would be surprised at the request, but more than happy to provide the education.  I find that resistance to such requests is more a reflection on the possible lack of knowledge and/or understanding of the person you are talking with rather than a lack of necessity.  Any major change in gear should automatically be followed up by time in a pool.  More on this in a future post.

So, fins are the engines.  With such a good engine on our feet, it means we should not need to use our hands to dive.  If you are diver, this is the one thing, once you are aware, that will have you looking at divers very differently.  You will begin to notice just how much even some highly experienced divers use their hands for all sorts of movements.   Newer divers tend to use their hands a lot.  Well, new divers that are not trained to not use them.  But, the use of hands for controlling our diving is a crutch and should not be happening.

I am well known for asking people in my talks, “What are your hands used for in diving?”  My answer is usually a less polite version of “for holding stuff”.  Here is the problem if you rely on your hands in any form to control yourself while diving.  The second you need to use your hands from something else; you just handcuffed your ability to dive.  So, when you need to actually hold something, now you cannot dive as well as you did before having to hold something.  Precision Diving is about being able to dive just as well either way, in fact all the time.

Let’s go back to our first post example of handing a diver a camera.  Yes, there is the distraction factor.  But, you very quickly realize that the diver with the camera had better be able to control their diving without the use of their hands.  Because they just tied them up.  It is easy to see.  Those that have good skills and have learned to not use their hands make out better than those that have not, often in dramatic fashion.

This is true of dogmatic arm and hand positions as well.  Most of which come about because the diver simply does not know what to do with their hands.  So, they ritual a swimming position that locks them up.  Well, this can work in the short term to have them looking better, but the same problem remains, when they need to perform in another way it throws the whole system into a tailspin.  Performance suffers.

Try not to get locked into any one way of where your hands should be.  In fact, get good at being able to dive the same way no matter where your hands are and in lots of places being used for lots of things.  Just not used to control our diving in any way.

I will speak about the hands in front swimming style and other issues later in this post.

We have dialed in our fins and we are not using our hands.  The next thing to do is make sure you understand swimming.  Propulsion through the water is a lot of work.  So, we want to make sure we do this as efficiently as possible with the choices in swimming we make.

I ask people all the time, “what is the most important part of swimming when we dive?”  A lot of answers come flying back.  My answer surprises most.  The glide.  Gliding is why we swim.  Not the movement of swimming, but the motion we gain after we kick.  You see a lot of divers just always finning.  They clearly do not understand this concept.

The next time you dive, ask yourself, “Self, how much glide am I getting out of my kick?”  The glide is the space between the notes on the sheet of music.  It is to swimming what breathing is to all of diving.

This is why we need to talk about movement as a whole.  Our glide is a function of swimming, but also a function of how much water we need to move out of our way as we swim and resistance as well.  More of this is a sec.

As a diver, there are four finning styles we should know: Flutter, Modified Flutter, Frog Kick, and Modified Frog Kick.  The modified version of each is simply a way to prevent the fin wash from going down to the bottom when you want to make that decision.  Which is most of the time.  Reach out to your instructor for help and if not them find one that is happy to help.

There are many other finning styles and it is fine to learn all of them.  Just make sure you master these four first.  Really, you want to get very good at each one before you add a new one to the mix even for these four.  Until you are sure your kick is the best it can be it is going to be pretty difficult to figure out if other factors are affecting your ability to glide between your kicks.

Once you are feeling good with the kick, it is good to get some video footage of you doing it.  Video analysis is the best tool to work on improving your performance.  Also, it is much easier to see what you are doing and understand than trying to hear someone’s explanation of what they think you are doing.  It is best to have both.  With the advent of inexpensive high quality video systems, this is pretty easy to accomplish without needing someone dedicated to doing the video.

Now, kick and get moving.  Once you get a few kicks in, see how long you can glide after each kick.  Begin to play with how you kick and how often you kick.  Which ways maximize your glide?  This will change with your kit, your conditions, what the water is doing, and several other factors.  Optimize and maximize your glide.  The easiest and best place for this work is in a pool.  The pool tends to minimize the impact of any factors outside of your performance.

Once you get good at moving forward, you can begin to work on flat turning.  Flat turning is a fancy way to say turning using your fins to do so without any forward movement.  If you get good at Modified Frog Kick first, then turning yourself with just the use of fins is easier.  This helps provide that control that most feel they gain with the use of their hands.  The fins will always do it better and more efficiently than your hands.  Plus, you are more likely to have control of where the wash of that movement goes.

We work on flat turns because it is more difficult to do stationary.  Once we get good at these, we can easily add slight movement in as we swim and glide to create turns.  The layers of subtly grow as you get more refined in your control.  Greater ability to control our diving is what gives us confidence.  The faster that happens the more likely we will enjoy our diving more.

Eventually, you can learn to use your fins to move backwards.  Yes, even with split fins.  Moving backward is helpful when you are unable to turn around easily and often used by photographers when they are head down and looking under reefs or ledges.

All of this is connected with breathing and buoyancy.  How and when we breathe and where our buoyancy is has profound impacts on our swimming.  As Precision Divers, we use our control over all of this to optimize our performance.  It is important we understand and have automated all our foundational skills so we can build to this level of integrating them together.  If that integration is difficult for you, then go back to the individual foundational skills and work on them.  The better the foundational skills are in basic applications the more likely it will be easy to use them in an integrated fashion.  More in a future post on this topic.

If you begin to watch divers, which you will now, you will see that often swimming is used to compensate for other issues in the foundational skills.  It is pretty common to see divers try to swim out of bad buoyancy.  Swimming creates lift and that forward movement can have it appear to the diver that they are neutral because of the forward movement creating water flow over the divers body at a different speed above the diver than below.  However, when the diver stops they immediately sink.  Not to mention what the hard kicking does to their visibility and the environment, always fun for your fellow divers as well.

We know from the post on breathing that we can use our breathing control to compensate for this in the short term.  Often, most divers try to swim out of it.  Stop being that diver.  If you feel you need to move to be neutral, do not swim more, fix the issue then swim.

Clearly, you are not going to get as much glide if you are swimming all the time because you are trying to fix the issue with your buoyancy.  In fact, I doubt glide is any where near being on your mind at that point.

When we swim we should be able to stop at any point and not move at all.  Well, unless we want to create that movement with our breathing control.  Hopefully, with some forward glide at the end of the last kick.  That is control and that should be our decision.  Not a happy accident.  So, make sure it is you making that happen at all times.

Other things like swimming backwards or backing out after looking under a ledge can be made easier by thinking about how we use our breathing as we do it.  We know if we choose to cycle our lung volume near full our head tends to raise.  So, if we cycle lung volume lower in the lung we can help to create a rise in our feet.  Or perhaps our feet are already slightly elevated.  Either way, we can use our breathing to help the backward movement out a bit.  A bit of positive buoyancy controlled by our breathing as we create some backward movement is going to help our up and away movement.  This reduces the amount of finning we need to do in order to create the desired backward movement.  Also, it allows us to use less backward kicks to make the desired movement happen.  This is a good use of lift to help desired movement.

Hands locked in front is being seen more and more these days.  For most, it is just compensation from being uncomfortable with their hands and trying to lock them up so they will not use them.  But, it also generates lift.  For most, it is compensated for slight negative buoyancy.  Subconsciously, this could have come about from feeling better about not losing control via positive buoyancy when they were newer or perhaps just a bad habit.

It is not necessarily a bad habit to have the hands locked in front, but you should be able to dive exactly the same with your hands in any other position as well.  It creates the same problem as we discussed earlier in this post.  What happens when you need to actually use your hands for something else, like holding something?  If the answer is nothing happens, perfect.  Then, this truly is a choice.  If the answer is you do not dive as well, it needs to be fixed.

Use of lift in our swimming is a very important idea.  As you progress, you are going to realize that you can use lift and buoyancy to move without swimming or to aid our swimming.  You might even be told you move too fast and you respond with I was barely kicking at all.  We can use negative lift on descents to literally fly on a down slope.  Our fins then become rutters helping to change direction.  If we want to flatten out we simply inhale a bit more, drop the tips of our fins a touch, and cycle our breathing there to stop the descent and exhale to restart it.

We can do the same on ascents, using our lung volumes and how we cycle our breathing to ascend without ever having to swim.  This minimizes work and provides a great sense of control and confidence.  All we have to do then is breathe and let bits of gas out of our BCD.  Super easy to slow the ascent when it is our breathing and lung volume doing it.  There are submarines that use changes in ballast and where it is held to move through the water without the use of propellers.

Refining finning skills and adding new tools to your performance toolkit is important.  We also need to look at how trim and hydrodynamics impacts our movement as well.

Water is heavy.  I will try to keep the math to a minimum.  If we are moving through the water, we are moving water because we are forcing it to flow around us.  Even small changes in how we make contact with that water can have real impact in the amount of work we need to do to move it.

Ideal positioning is how we optimize that.  If we are not moving, then ideal positioning is not so important.  If we are hanging out on a safety stop in blue water, it is not so important to be in any position.  There is some research that shows some positions may benefit off gassing better than others, but there is still not much data either way.  The point is; if we are not moving, how we move is not going to be in play at that time.

Ideal position is a flat position that minimizes the surface area that interacts with the water as we move.  Generally, the torso is parallel to the bottom with a slight arch in your back.   This helps you to see forward without having to crank your neck and/or not having to elevate your head, which would create more drag.  Legs inline with the torso with a slight or more bend in the knee.  This will depend on the kick you are selecting.  This position is your default position when near or close to the bottom.  It will be comfortable and easy once you get used to it.

One easy technique to help you “feel” it is to go to the bottom of the shallow end of the pool and be a bit negatively buoyant.  You should feel the pool bottom from you knees to your shoulders for the most part with a slight arch to your back.  Inhale and create some positive buoyancy and then drift back down and see if you can land in the same way feeling the same things.  It is a good exercise to help you feel it.  I find video really helps here.  Project it on to a white board and draw your horizontal line inline with where you should be.  If you match the line you are doing great.   Assuming that is the goal at the time.

If you are going to put this much work into your positioning, you want to make sure you streamline your kit to match your work in streamlining you.  So, watch your accessories.  Clip them in tight to your body.  If you are a fan of retractors, figure out how to use them without having them have what is attached to them dangle down.  Consoles and SPGs should be brought in tight to the body and clipped up.  No sense in having them create drag when they are not being looked at.  Optimize your kit by routing hoses down and in.  One small thing is not likely to make or break you, but lots of little things can add up to more than you think.

Water is heavy and having to move more of it requires more work.  More work means more gas used and less time underwater.  The goal is to minimize anything that is unnecessary work.  Seawater is 64 pounds per cubic foot.  For our metric friends, that is about a kilogram per liter.  In theory, if I present one square foot of surface to the water and I swim one foot forward, I would need 64 pounds of thrust to make that happen.  If I move the same foot with only somewhat poorer streamlining and present three square feet of surface to the water, I now have to provide 192 pounds of thrust to move a foot forward.  For our metric friends, the numbers do not matter, the message is clear, bigger surface area, much more work.

So, small things like elbows sticking out, or a console and hose, or poor swimming technique that stops glide, or a combination of all or more can quickly add up to a lot more work.  This means more gas consumed and less bottom time available.  Several small improvements in streamlining will add up.

Drag also matters.  Drag punishes speed.  You need to move a lot of water out of your way as you swim.  This takes work as we have seen.  If you want to do that while going fast, it takes a lot more work.

Drag Equation


FD is the force of drag, which is by definition the force component in the direction of the flow velocity,[1]

ρ is the mass density of the fluid, [2]

v is the velocity of the object relative to the fluid,

A is the reference area, and

CD is the drag coefficient — a dimensionless constant, e.g. 0.25 to 0.45 for a car.

Drag is calculated with velocity being squared.  The important take home message is that the faster you go, the more you have to work in a function of how fast you go multiplied by itself.

I like to say with diving you need to slow down to speed up.  If we move slower in the water, it requires less work.  If you have good trim and streamlining, that is even less work.  We want to give time for the heavy water to move past us.  Ironically, when we move slower we get more glide, we get more out of our glide as it is more of our movement per kick.  Also, it is likely that our technique is better when we are not rushing.  Plus, our technique does not have to be as good when we more slower.  Of course, we want to optimize our performance at all times, but there is a tipping point with work and speed where you will move faster and further by slowing down than if you try to go faster.  You want to find that point and refine even more.

Technique matters.  I have asked students to swim lane lines on the bottom of the pool and to get to the other end as fast as they can.  They go screaming out and forget all technique, gas pumping through their lungs with a stream of bubble arching up behind them.  I time the effort of course.  When they are done, I ask, “What happened to your technique?”  Oh yah.  I then tell them to repeat the swim again, this time as fast as possible, but with the very best technique you can perform and maximizing glide.  Which one do you think is faster?

The result is dramatic.  Often, the results are 20 to 30% faster even though they feel they were going much slower the second time through.  Thus, proving to them that slowing down actually speeds you up.  Literally.

If you are not able to stop at any time in your diving and stay in the position you want to be in, then you want to work on these techniques.  You can move weight higher or lower on your body to help, but it might be a better answer to look at potentially other choices in fins or other gear if the stuff you have is creating a problem that other kit will fix easily.

If you are diving dry, then learn to manage your bubble in your suit.  Trim is much easier in a drysuit because your buoyancy is spread out over your whole body.  But, you want to make sure you become intuitive with managing and breaking that bubble up into smaller pieces allowing you to feel in control of where your buoyancy is in the suit.  Bubble management, if you will.

As you progress, you will refine your awareness and techniques.  With this growth in your ability to dive well, you will work on subtler and subtler areas.  Also, you will become much more sophisticated in the techniques you can use to control your diving and have a lot more tools to do the same thing in different ways.  I will post about more subtle aspects in smaller posts in the future.

Be better this dive than the last one and better next dive than this one.


As I have promised, the first post on Buoyancy has arrived.  Pretty much everyone would agree that buoyancy is one of the critical skills in diving.  What does that actually mean?  We spend a lot of time discussing the topic in pretty much every course, but do we ever do a good job truly getting the diver to understand what this means and what it looks like when we are good at it.

It is impossible to discuss buoyancy without discussing breathing.  It is why that post came first.  Buoyancy is so critically linked to how we breathe and how we change our breathing that really the two are very much linked.  It is also why we need to master and understand ideal breathing for scuba prior to trying to improve our buoyancy and the control of it.  Or use lung volume and where we build volume in our lungs to further refine buoyancy.

That is what caring about and paying attention to this results in, control.  With control comes confidence.  Ideally, each diver should be confident in their diving within appropriate development for their level of progress in training and experience.  If you do not feel confident in your diving at any level, get back to the basics.  It is the foundational skills discussed in my first post that will bring you the confidence and execution you desire.

So, now that you are working on ideal breathing, we can look at how we can dial in our buoyancy control.  Working position is tied to buoyancy, but pure buoyancy control is what needs to be mastered first.  This means that we should be able to stop at any time in our diving and not move without a change in lung volume.  So, we are neutral at all times.  Unless we choose not to be.  It should be a choice.

There are times when you will choose not to be neutral.  On the surface, we usually choose to be positively buoyant so we can rest or swim to the boat or dive site.  I find I have to remind new divers and sometimes not so new divers to use their BCD on the surface to not work once their head breaks the surface of the water.  It is all about minimizing work and making diving easier where we can.

We may choose to be negative on the bottom to stabilize ourself in a nonimpactable environment while taking pictures or during an experience that requires us to stay on the bottom.  If I am working in a strong current and hand pulling on the bottom, I usually like to be a bit negatively buoyant as well.  Most professionals while teaching use negative buoyancy to help if a new diver has a problem and the instructor needs to arrest an assent.

For the most part, as divers we want to be neutrally buoyant at all times once we leave the surface.  Being neutral is the weightless inner space experience that we all as divers crave and speak to non divers about as being magic.  It is one thing to know what is feels like.  It is another to have such possession of it that we are able to use its control to appear to be magic.

Buoyancy changes take time to happen when we dive.  This delay can be different at different times depending on depth, gear configuration and other factors.  But, for the most part when we make a change in buoyancy it takes two to four seconds to really take affect.  This means we can use our control of buoyancy to compensate for wave action, picking up a weight, or wanting to use ballast to drive movement along with so many other things.

It also means we have to be patient and plan for this delay in action.  So, we have time to work with it, but also if we do not pay attention issues can get worse over time.  This is all assuming diving open circuit scuba.  Buoyancy on a rebreather is very different and not so tied to changes in lung volume as open circuit scuba.  I will discuss rebreathers in future posts.

In our beginning scuba courses we are told on descent to equalize the pressure in our ears and sinuses.  This is a very important thing to do as it is the most common injury for most divers if not done properly.  Easily avoided if we do it early and often and before we feel anything.  More on this in a future post.

However, the corrective action prescribed if there is an issue is to kick up a bit and if negative add some air to the BCD.  Conversely, if someone begins to drift up a bit becoming slightly positively buoyant we say let some air out of your BCD as the first action to take.

Why not suggest that the rising diver first exhale and then emphasize breathing with a reduced lung volume or on the bottom of the breathing cycle first and then make the adjustment to the gear?  Additionally, on the negatively buoyant descending diver, why not tell them to inhale and then emphasize the upper portion of the lung volume and then take corrective action with their gear?

Of course, ideal breathing needs to be mastered in order to be able to chose to deviate from it in this way.  But, is it not more controllable and more intimate to use our control over our breathing first than train people to go to their gear?  Going to the gear first, as almost any instructor knows in newer divers, is not quick nor familiar.  I would bet that any new diver knows where their lungs are.

If we all build a strong connection between our breathing and our buoyancy we can effectively add five pounds of negative or positive buoyancy or more at will within seconds simply by how we choose to change our breathing and emphasize cycling breathing at the lower or upper end of lung volume.  I am suggesting this is going to help divers feel that they have more control and I think we can all agree is more accessible, intimate and quicker than fumbling for a deflation method only to have the wrong end of the BCD facing up.

Choosing to change breathing may not solve the problem completely, but it slows everything down.  It provides time for a calmer approach to finding the right item to make more adjustments to buoyancy and the perspective to think about being in the correct position to do so.  Most of us have seen the newer diver facing head down trying to dump air from their BCD while swimming down fighting positive buoyancy only to have the air in the wrong place in their BCD for their attempts to be able to do anything.

If this diver were to exhale and choose to deviate from ideal breathing by cycling on the bottom of their lung volume, they would take most of that positive buoyancy out of the situation.  It could bring them back to neutral or even slight negative buoyancy or at least immediately drop the urgency of the situation down several notches.  This gives the diver more time to think through why what they are trying to do is not working as they had hoped it to.  More time, generally means less stress and more likelihood of success in correcting the situation rather than drifting backward toward the surface.

This is only one example of how much more layered the subject of buoyancy is.  It is easier to see the results in an obvious situation with a newer diver.  As you get better, you will see that subtle changes in where you emphasize lung volume can play a role in trim and swimming.  How you release lung volume or add it can change lift and your center of buoyancy.   We can begin to use our breathing to actually help us move better through the water and also allow us to work less.

I will speak to movement and trim in future posts.  Buoyancy control and working with your breathing can allow you to change how you ascend.  We are taught to reach up, look up, and come up, swimming to help the movement.

What if we were to ascend by using our breathing to emphasize different areas of lung volume on average to create rises toward the surface or to drop down a bit on a safety stop or to slow our ascent and adjust our BCD?  When mastered, ascents can become literally almost no work.  They are also highly controlled and slow because we are intimately in touch with the movements because it all comes from our control of our breathing and our lungs.  Of course, we still need to vent excess gas from our BCD or drysuit and we do not want to hold our breath.

So, buoyancy is often talked about in diving and I know that we could fill a room with instructor trainers where “good buoyancy” would make everyone’s list of important skills to master.  We need to expand our understanding of what this means.  We need to tie the discussion intimately to breathing and how we find ideal breathing and how we choose to change from ideal breathing if we need to do so in order to affect our control over our buoyancy.

Buoyancy control is extremely important to good diving and certainly is foundational to the Precision Diver.  It just does not live in as much isolation as we have been used to dealing with it in.  In the near future, I will explore how breathing and buoyancy work together in how we swim and our trim in the water as well.

The foundational skills all work together built on top of our performance mindset to hold up the roof that is performance.  With performance comes confidence in our diving.

Bahamian Adventure

I am back in the US after being in the Bahamas at Stuart Cove’s working with Joi Ito on his PADI Instructor course.  See his post. Instructor training is not so much about teaching skills or knowledge, but more about helping the candidate become comfortable with presenting what they already know in an engaging and educationally valid fashion.  Joi is already a seasoned public speaker, it was more formatting than great effort.  But, it is fun to see even very experienced people create new connections and evolve into new roles.  He did very well, by the way.

While we were there, Joi had the opportunity to also work on Instructor level specialties.  One of these specialty areas was shark awareness.  I will let his post speak for the experience.  It is something that needs to be experienced to fully understand.  I have been working with sharks for over 25 years and it is always amazing to be honored with their company.

Sharks have had the same appearance of today for over 100 million years.  Generally, this means their body shape and function is pretty good for what they do.  It is one of the coolest things about watching them, they are almost perfect at what they do.  It was fun to get to share this with Joi.

Photo by Cathy Ridsdale Stuart Cove's

Diving at the resort is quite good, especially off the beaten path.  It has some of the most pristine wall diving I have found in the Caribbean.  They also have tons of wrecks and many of which are very shallow, which allows for longer dive times and better conditions to practice penetration technics.  Plus, everything is a quick boat ride.  It makes for a very easy field to play in.

Silky Shark (Carcharhinus falciformis). Photo by Cathy Ridsdale Stuart Cove's

We also took a trip further afield to visit with Silky Sharks (Carcharhinus falciformis).  They reside out in the blue and one of the best areas to find them is around the sounding buoy off of the island.  The buoy is moored in 6000 feet / 1829 meters of water.  When we pulled up and tied off there were two Silkies already there to greet us.  I love being out in the blue with bottomless water and incredible visibility.  Then, to get to enjoy pelagic sharks is even better.

Joi in the blue with Sliky in the background. Photo by Cathy Ridsdale Stuart Cove's

The resort has a robust photo and video department where all of the shooters were quite skilled.  It was very helpful to have their assistance from time to time to help document the trip and allow me to focus on teaching and grab some GoPro footage now and again.

I would have to say I was pleasantly surprised by my visit and would go back any time.  It is worth the short flight from Miami to check it out.  For teaching, you cannot ask for more choices in dive sites and almost any specialty area can be conducted there.  Plus, the staff were very helpful and understanding of the needs for teaching.

The Performance Mindset

Life has been busy as can be.  I promised more on the performance mindset.  I will have ongoing posts related to this topic, but I wanted to make sure that I get a post out specifically about it now.

The last two weeks I went from busy in Australia to a thirty-six hour turn around in LA to come to the Bahamas to work nonstop.  I know, rough life.  But, it reminded me of all the things that diving helps us do and actually not do.  When we are underwater, diving allows us to escape mobile phones, commutes, daily grinds, E-mails, and so much more.  It is part of why I do it and likely all of us.  It is also why how we think when we go diving can be as important as how we dive.  In fact, it may be how we think that is how we dive.  At least to some extent.  Or perhaps mostly.

Diving has changed my life for the better and forever.  The best friends I have met relate to and are around diving.  It has changed me as a human being and how I see and interact with the world.  It is part of what makes diving so beautiful, that immersion in water brings us places that almost nothing else can.  Even if we dive the same location again and again, it is never the same dive twice even if we were to staple the fish to the reef, because we are never the same person as the dive before changes us forever.  So, we cannot have the same dive twice, no matter what.  We are never the same person the next time through.

Diving is so special because it touches us so deeply.  All of us who dive understand this to our core whether we “get it” consciously or at a subconscious level.  For those who are contemplating beginning to dive, I would just say enjoy every moment as diving brings many of them.  Big transformations are part of it, but often it is the littlest of ones that ripple through our lives too.

This is why what and how we think about diving while we are diving is powerful and needs to be considered.  More than being considered, we owe it to ourselves to make sure we do the best we can with our thoughts because diving is so powerful.  We have a duty to make sure that something so important and powerful is respected.

More importantly, it is just more fun to be good.

So, how do we begin our work?

The performance mindset begins with us.  One of the things I love about diving is that we cannot hide from ourselves in the water.  We all find our moments of truth in the water.  Great circumstances bring big pleasures and change us, challenges and difficult situations tells us volumes about ourselves and further bring to our immediate awareness areas that we may have tried to hide from in ourselves.  These can also change us for the better expanding our awareness and allowing us to be more adaptable after.

If we do not train how we think about diving, the effort to learn more about diving and being better is hampered.  What I am suggesting is that our mental training is as important if not more important than skill mastery or taking another course.  How we do these things matters as much as actually doing them.  Execution is as important as accomplishment.

As I presented in my first post, we need to make sure we have a picture in our mind of what it means to be a great diver, an elite diver.  We have not been presented with a simple well thought out snapshot of what this means.

This elite diver concept is so important because we will rise to the level of the vision we have for ourselves.  If we do not have a clear picture of what is means to be good at diving, how can we have a hope to arrive at a point of something we do not understand or can easily picture?  We can put 100 of the best instructors in the world in a room and we would likely have some common threads presented as to what it means to be good at diving, but it is unlikely we even share a common language about it.  The diving industry does not paint a clear picture either.  It is not about blaming anyone.  It is about providing something that almost all other activities can easily provide.  A clear, easy, simple sound bite style quick answer or someone to point to for a clear visual.

RJ Barbaro at Bondi Beach Skate Park.

So, lacking any clear, simple, or easy answer, let’s take a look at what might be this undefined mystery diver, the elite diver.  I think we can all agree that an elite diver should be in control of their diving at all times.  This would include all that their actions impact or do not impact with all that is around them.  So, it is not just performance, but how that performance creates or does not create issues or impacts on all other factors around them.  For the most part, this level of control is automated or unconscious.  Or you might call it intuitive.

This means that the diver is able to adjust for wave action, or current, or motion acting on them and yet still appear there is no impact on their diving.  It might feel very different internally, but the outside shows no changes.  An elite diver only deviates from ideal performance because they choose to.  Rather that be because there is a need to affect control for other purposes, or to have impact on the diving environment, or to compensate for actions in the environment that will take the diver out of ideal performance.

The diver is in control as much as is possible while diving and nothing happens without a decision by the diver to do so.  So, unideal performances are a choice on the divers behalf or a mistake.  The mistake is immediately and naturally registered in the mind as out of ideal.  This is looked at and address that dive or the very next one.

If we can build a simple picture of what we would look like as an elite diver and be very candid and honest with ourselves as to where we are or how far away we are from that picture, it is the base that will help us improve rapidly.

If we can see it, we will rise to our vision of what it is we are shooting for.  That “end goal” becomes the guide and foundational image we carry forward to build our skill mastery upon.  Rather than work on skill mastery and just hope we have a “happy accident” that helps us find our way to how to make it all work together.

It is a cart before the horse problem.

So, we need to work on how we think and the vision we carry forward with our diving.  If we can internalize and clearly see what it means to be an elite diver, it will provide a road map of where we need to go next.

Joi Ito on Bahamian wall dive. Photo by Cathy Ridsdale courtesy Stuart Cove's

This can be easier to see than do, but that is the beauty of diving, you must do the milage to master the craft.  You have to dive your way into the thinking and out of bad habits.  It is the rituals and way we view where we are supposed to end up that create our diving habits.  These need to be guided with this clear vision of how it all fits together.

So, how we think matters when we dive.  We need to make sure that we establish that piece of video or vision in our head about where it is we are headed with our diving.  Once we establish that, we need to make sure we stay aware when we dive to this vision we have established.  The feedback loop continues forever, but becomes more automated with each moment of application.

More soon.

Breathing for Scuba

I want to get into more detail about the breathing we should be doing when we scuba dive.  As I mentioned in my first post, it is our first and most important foundational skill.  Well, not that they are not all important, but pretty much everything in Precision Diving is based and results from how we breathe and the choices we make around that.

I mentioned the foundation of the performance mindset as well.  I will be coming back to that in a future post very soon.  I thought it would be a good idea to begin this more specific discussion related to breathing sooner rather than later.  This relates to open circuit scuba breathing.  Rebreathers I will address later.  A few slight and not so slight differences there.

At my presentation at OZTek 2011 the vast majority of participants when I asked how we are told to breathe said slowly and deeply.  When I asked, “Have any of you ever actually been shown what that truly means or been taught it or had it demonstrated to you, ever?”  That moment is a good moment, perhaps many of you had that when you read the first post or you are having it now.  That realization of hey wait a minute, really, yes, wait, HEY, it never happened.  Fun to see that lightbulb go on for people.

If you are highly experienced you might find you are feeling a bit of resistance about now.  Don’t worry it is fine.  This too shall pass.  It is not to indite the industry or wave my finger at it.  I am part of it.  I simply point this out because if we are not aware of it we cannot be open to talking about it.  We think we know, we assume that since we have been breathing, for the most part since the day we were born and it is automatic, that surely we must know how to breathe properly.  Well, we don’t, well unless you were trained how somewhere usually.  If you already get it, great.  Perhaps after this there will be some common language or structure to at least be able to more easily talk about it in the future.  At worst, you might pick up a few new details.  For the rest, you should see a decrease in how much gas you use while diving almost immediately.

I am not pretending that I am inventing most of this.  I am just bringing a language and a structure to it that we can use to talk about it more easily.  So much of this stuff I struggled with trying to make it come to life in my clients until I understood we were missing the common framework and language to speak from.  It was like not being fluent in the same language and carrying on a conversation when there was no obvious common references to work with.

So, I bring this concept forward early in the discussion because it is so critical.  Breathing is the metronome and cadence of our diving.  I will bet that if you have ever had a not so happy dive, that when you think back to it, it is very likely that your breathing was not ideal.  In fact, I bet that your breathing was all messed up.  So, if our breathing is messed up, it is likely that the diving is not too far behind it.

Diving is a powerful thing.  It changes you forever.  Do we ever want to risk  having such a powerful thing be a negative in our lives?

If we are aware of breathing and gain full access to all the confidence and control it can bring for our diving, you will look back and wonder how you ever managed to enjoy it as much as you do now.  It is the most intimate and quickest way to make small and large adjustments in buoyancy, trim and help or hurt how we move through the water.

Think back to your open water course (beginning) and remember that we are told to move up a bit if we have difficulty equalizing our ears or sinuses.  Generally, we are told to add some air to the BCD or swim up a bit.  We are not told to use our breathing to focus on cycling through a more full lung volume.  Or we are told if we begin to move toward the surface without wanting to because of a bit of positive buoyancy, we should let some air out of our BCD.  Why not tell the diver to cycle breathing momentarily on the lower part of their lung volume?  Of course, it is important to make the adjustments eventually with the gear.  But, what is more accessible to the diver, their external kit or their lungs?

Effectively, if we learn to use our full lung volume and can control it, it can be like adding or removing five pounds (2 kg) of buoyancy far more quickly and controllably than waiting to find and fix the kit.  With the lag in changes in buoyancy there is time to find and fix the kit if we can mitigate the issue with how we breathe.  Rather than, especially the new diver or student diver who might not be automated with where to find and adjust their kit, having to make sure they are in correct position and have the correct bit in the right place.  This more immediate control and ability to make more major adjustments will allow you more control and that brings with it confidence.  There are of course limitations to how much we can affect change with how we breathe, but it is certainly more than most of us are aware of or has ever been actively mentioned to us.

renjith krishnan / click on Image for portfolio.

The nice thing is that these types of minor corrections and getting the hang of things becomes easier because we can be less quick about it potentially.  Instead of worrying that if we miss the correction a few times we will have more and more difficulty.  We can use how we breathe to create that space where we can take a pause to think through what needs to be done correctly.  We can mitigate the issue and with it be more likely to be able to address it the first time.

Breathing is critical and will be discussed many more times.  Once you begin to master your breathing you will begin to see just how many ways it has impacts on your diving.  As it becomes more automated, you will not have to think about it as much and the adjustments will also come without having to think about it.

This is when you have the appearance that things do not affect you like it does other divers.  They will be thrown a bit by some surge or waves above and you don’t really move.  They might find it is a bit of a struggle and feel like they have less control.  We will talk about it in a future post, but as you evolve with the skill the levels of detail gets deeper and deeper.  Like so many of the others things in diving, we are training new default responses.  This is one of them, just like the rest.

Below is a piece I wrote for instructors about teaching breathing for scuba over six years ago.  It never ran with the publication that asked me for it.  While it is not geared toward the diver, it gets the details across and I think you will find it an informational resource.

Breathing for Scuba:

Lessons from those who only have one breath to do what they have to do.


Freedivers do their dives relying only on the breath they carry with them.  So, you can bet they make the breaths leading up to a dive really good ones.  In fact, freedivers actively work on how they breathe.  The old adage in scuba of deep slow breathing is true, but only scratches the surface of what is involved.  It is almost universal that breathing is not really taught in a scuba course.

Freedivers use deep breathing techniques prior to a dive to optimize the gas exchange in their lungs.  They use their physiology to its full advantage to insure they have the maximum use of their last breath.  Scuba divers benefit from these techniques while diving gaining maximum breathing efficiency and extending the duration of their gas supply.  Unfortunately, the vast majority of scuba divers are never learning how to breathe properly.  This becomes very apparent when diving with virtually any group of divers.  Breathing remains one of the great under utilized tools of diving.

Simply put, the visual image used for proper breathing is to fill your lungs from the bottom and empty them from the top.  Seems simple enough, however very few ever seem to master the technique or more appropriately are never taught the technique.

The proper technique is known as diaphragmatically initiated breathing.  It takes advantage of lung physiology.  It is important to understand a bit about the lungs to understand why how you breath is as important as breathing at all.  All parts of the lungs are not created equal when it comes to gas exchange.  Most divers breathe primarily in the top of their lungs.  This technique reverses that.  The bottom one third of the lungs is responsible for seventy percent of gas exchange in the lungs.  This is why it is critical to keep the lower third of the lungs occupied with gas for as much of the breathing cycle as possible.

So, the next time you teach an open water course, spend some time teaching your clients to do something they think they already know how to do, teach them to breathe properly.

Have your clients begin to fill their lungs from the bottom first by actively extending their diaphragm out while not using the chest at all.  Now, this is not the sexiest way to look, but it does allow the lungs to fill from the bottom up.  Have them concentrate on just using their diaphragm to breathe with.  This looks like a pooch in the belly moving in and out.  Once they are able to just breathe from their diaphragm, have them add their chest to the inhalation about half way through the expansion of their diaphragm.  Once they have a comfortable full breath they should pause in a relaxed way for a second or two.

The number one rule in scuba is to never hold your breath.  This is not a forced hold of their breath, but rather a pause in a relaxed way.  If a depth change were to occur the air would simply be exhaled.  It is important to emphasize to your clients that they should never forcefully hold at the top of the breath.  It should be relaxed enough to allow for any expansion of gas in the lungs to easily pass and be exhaled.

The next step is to extend their exhalation.  This can be done using the tongue on the roof of their mouth.  Freedivers use pursed lips, but that is tough with a regulator in your mouth to do.  The diver should feel as if the gas is leaving their lungs from the top to the bottom.  The ideal is to keep the lower lung inflated for as much of the breathing cycle as possible.  Once mastered this new breathing technique will take anywhere from ten to fifteen seconds to complete.

When done properly, the diver begins to develop a breathing parameter.  The concept of a breathing parameter is an important concept to introduce at all levels of training.  A breathing parameter is the rate, depth and way you breathe while you dive.  We need to optimize our BPs at all times when we dive.

When diaphragmatically initiated breathing is used in scuba, the diver does not need to change breathing parameter when experiencing changing workloads as there is no more efficient way to exchange gas in their lungs.  Considerable work, time and effort should be used during all training to correct the diver’s psychological urge to lose ideal breathing when experiencing exertion.  There is no reason to go back to rapid shallow breathing when faced with increased workloads as that is only going to use gas faster and make the diver feel worse and more starved for gas.  This is mental training as much as it is physical training.  We need to reverse the tendency of divers under stress to consume gas rapidly with the least efficient way of breathing possible.

This is a foundation of becoming a good scuba diver.  There is no better place to introduce foundational skills than at the very beginning.  It is important to establish this foundation and emphasize that your clients should go back to this as soon as they realize they are out of ideal breathing.  There are times when all divers leave ideal BP.  Teaching divers to correct bad performance is often more valuable to them than just learning the ideal performance.  The easiest way for someone to regain ideal breathing when breathing rapidly is to extend exhalation.

The active component of our breathing is the inhalation phase, exhalation is actually the relaxation phase of breathing.  So, it is very important to minimize any effort while exhaling.  Regulator quality has a great deal to do with exhalation resistance more so than inhalation effort.  So, to regain proper BP, it is better to begin to relax exhalation.  Teach your clients to begin to extend their exhalation on each breathing cycle.  As they begin to relax, they will regain their ability to use ideal breathing.  It is generally a good idea to have them stop their activity while they regain their BP.

Now, there are times when scuba divers want to not be in their ideal BP.  This occurs when adjusting buoyancy and controlling tight hovers.  Extending inhalation or exhalation is still fine.  Just make sure that your clients do this still filling from the bottom and emptying from the top.  Teach them to not hold their breath to hold position but to maintain a tighter range of lung volume while doing so by inhaling sooner and/or not exhaling completely.

As divers gain experience and rise in the ranks, proper breathing becomes even more paramount.  At advanced technical diving levels the maintenance of BP can mean the difference between life and death.  So, work with clients from the beginning to help them establish the breathing foundation needed for them to be confident and effective.  Freediving provides a great training ground to continue to work on ideal breathing.


I hope that helps shed some light on using breathing to improve your diving.  It helps a great deal to work with someone that can help you to learn to control your breathing muscles and work with you on breathing. There are many activities that utilize proper breathing techniques and will lend to improving your breathing for diving.