Freediving the MYTHS – 1.0 Breathing 100% Oxygen at depth after a Freedive.

Welcome! to FDHQ Title Series “Freediving the MYTHS”

Consultation of the Myth Busting brain Trust is made up of many of the worlds top trainers & experts from various major Diving / Freediving agencies and educators. The views expressed here are of first hand experience, science, logic and plain old common sense.


Foreword: Mike Wells

It is unfortunate that many practices in Freediving seem to go unchecked, unquestioned or challenged. In the sport of Freediving there is however some of the biggest egos on the planet, and considering there is no form of big dollar income professional Freediving competition series as of yet we can only guess it can be put down to “Look at me syndrome” or plain old hubris, therefore it is kind of understandable to see why someone may be reluctant to challenge the idea of a certain practice being inncorrect or dangerous, after all it takes alot of sand to challenge the ideals of your peers, a guru or perhaps a Freediving demi god!


In my opinion Freediving is far to easy and far to much fun to be taken so seriously, akin to Surfing, many people need to chill and accept criticism, bend a little and be able to look outside the cult box, after-all when you look at the key subject matter for the Freediving Myth busting series it really is just common sense. 


Here you will find the gospel on the get up and go to in Freediving practices. We intend to break down the old school barriers and bust down the doors of Mythology in Freediving. Many of these myths are largely due to outdated or misunderstood information & techniques that can commonly become sheep trends & unfortunately almost always end in disaster or at best a whole lot of time wasting from newcomers who observe first hand these strange happenings then forever question anyone and everyone about such events.

Keeping in mind Freediving really is just fun, easy, an adventure & most importantly anybody can do it successfully. Professional Big wave surfer Laird hamilton once said It has to be fun, if a sport is not fun then whats the point”.


Freediving the MYTHS” will hopefully influence the cult like mindset of the few out there, and introduce the newcomer or enthusiast to the simple truth about Freediving answers they seek. The information super highway for Freediving is officially open and the Speed limit is infinite, the fun factor is massive so fasten your seat belts as its not for the faint hearted 🙂 

“Freediving the MYTHS” 1.0 Breathing 100% Oxygen at depth after a Freedive.

Who would have thought that in fact breathing Oxygen could be a bad thing? most Diving enthusiasts would be familiar with the maximum operating depth (MOD) of a mixture of gas, this is where the depth in relation to (ppO2) of the gas mix can exceed a safe limit and can turn deadly if not taken seriously, especially when we talk about 100% Oxygen.



The practice of 100% Oxygen First Aid administration is well know in the Diving industry, from SCUBA beginner to advanced Tek Divers, the common safety message for Suspected Decompression sickness First Aid is breathing 100% 02 at the surface – But it is this next sentence which rings true and is the real take home message here (an injured diver should be transported as quickly as possible to a definitive treatment facility, during transport the use of 100% 02 is effective as First Aid). The administering of 100% 02 is FIRST AID, If a diver is injured / symptomatic then they must be transported to a chamber facility for assesment / re-compression therapy.

Neal Pollock, Reasearch Director for DAN USA had this to say Surface oxygen breathing is the best first aid for symptoms consistent with decompression stress. This would optimally be maintained while waiting for and during transport to appropriate medical care. All things being equal, a symptomatic Freediver should be immediately removed from the water. It is important to remember that the problem may or may not be related to the diving, and managing an injured or compromised person is much safer and easier out of the water. So, the default management protocol should be removal from the water, then surface level oxygen maintained through the stages of evaluation, communication and transport to medical aid”

So! what Myth do we find in Freediving about this? – What has been happening around the scene is the generation of the Myth that Breathing 100% 02 at depth after a Freedive is somehow a cure all for Freediving maladies, in theory a prophylaxis for DCS that was an apparent “possibility” during the last dive, Remember that if someone is in fact DCS symptomatic then they should be breathing on the surface 100% 02 on route to a professional treatment facility, not being encouraged to descend back underwater.



These days we find an epidemic sheep trend of Freedivers self administering positive pressure oxygen therapy! This is a very serious practice, ironically it carries far more risk than the non existing possibility of the DCS symptoms which was the supposed reason for administering the %100 oxygen at depth in the first place!

Without getting to deep into a theory lesson – %100 Oxygen / High partial pressures of Oxygen can be deadly, especially when breathed at depth by completely untrained people who have just expended a large amount of energy, (Ox tox – unconsciousness – seizures – drowning) are just some of the laundry list of dangers involved when untrained people are involved in breathing 100% 02 underwater.

Neal Pollock, Reasearch Director for DAN USA had this to sayThe burden to be met for safe in-water management is onerous, which should make it a fairly unattractive option. The risk of seizure from oxygen toxicity could badly complicate and already poor situation. The fundamental question, though, is whether breathing oxygen at depth is necessary. Given the relatively small total gas load a freediver carries with them, it is unlikely that there would be a huge benefit with the depth for oxygen breathing. That means that the hazard of in-water management should probably preclude such an effort”


End Game: The fact is, Anyone offering 100% Oxygen underwater or self administering 100% Oxygen underwater as a prophylaxis in Freediving is frankly doing it wrong! They are endangering themselves and others.

If yourself or someone you observe are DCS symptomatic (or other possible Freediving injury like Lung Squeeze etc), then you should be applying standard Diving / Freediving First Aid, Surface breathing 100% 02 on route to the medical experts, the last thing we should be doing is sending people back underwater, you simply do not have the training or knowhow to do so safely.

The big question we need to ask is why on earth are some people out there self administering or offering 100% oxygen therapy underwater? The plain truth is that specialists train for many years to be able to successfully do just that, to speak directly we need to see a stop to this sheep trend before we see a death, 100% Oxygen is not a prophylaxis for Freediving maladies, It is a First Aid for use on route to medical Professionals.

Neal Pollock, Reasearch Director for DAN USA had this to say“The need to breathe oxygen at depth would not be on my standard list for Freediving. Ensuring that each member of the group was appropriately trained in freediving and emergency procedures and prioritized safety above all else would be at the top of the list. The best day of diving is the one in which problems are avoided, or addressed easily when they are minor, or managed in a way that everyone involved can be proud of in the future”


Keeping it Real, Keeping it Fun, Keeping it safe 🙂


Mike Wells

Director of Leisure at FDHQ 😉