Rest in peace, Nicholas

It has been a few weeks since Nicholas Mevoli made the fateful dive that ended his life. I have waited awhile to write about this in order to give folks a bit of space to grieve, and also to let what happened and its ramifications sink in a bit and my thoughts about it mature in my mind. There is a lot that has been and will be written about this accident and this is by no means an exhaustive technical dissertation about all the issues. I merely want to apply my own perspective to the accident and not necessarily confine myself to established thought or teaching. Perhaps it will be useful. I certainly do not profess to have all the answers here, but I give it my best. Some of this will be theoretical and speculation on my part, as no one really knows for sure what Nicholas was thinking and feeling before and during the dive, what stopped him during his descent, why he continued to the bottom plate, and what precisely precipitated the squeeze. I hope in every way to be properly respectful of the memory of Nicholas and everyone's feelings in this.

Note: The Ability-Adaptation Squeeze Model, written after this article, introduces some new vocabulary that allows us to talk about all of this a bit more clearly. It says many of the same things as in this article but in a way that is more understandable.

Nicholas Mevoli's Ocean Competition History

Deja Blue III 2012-05-04

FIM AP88 RP88 Deep BO at 25 meters, squeeze 2012

World Championships


Vertical Blue 2012

CWT AP95 RP92 Pull, ruptured eardrum

Caribbean Cup 2013

CWT AP100 RP100
CNF AP56 RP56 FIM AP75 RP57 penalty
FIM AP81 RP81 2013

Depth World Championships

FIM AP91 RP80 penalty     

Deja Blue IV 2013-10-05


Vertical Blue 2013

Nov 10 CNF AP72 RP60 Early
Nov 11 CNF AP72 RP69 DQ Pull
Nov 15 FIM AP95 RP95 DQ Assist Upper Respiratory Squeeze, Ears
Nov 17 CNF AP72 RP72 DQ BO

As you can see from this history, he was at the very beginnings of his career, but still he had spent a good bit of time in competition (probably also during training) going much deeper than the 72 meters he was attempting on his final dive.

Final dive profile – CNF AP72

Dive commenced. He briefly paused his descent and turned upright at about 63 meters, probably to equalize. He then continued his descent, free-falling in an upright or sideways orientation. He paused briefly again at 68 meters and then resumed his descent. He reached the bottom plate, turned and ascended to the surface in an apparently normal way. He attempted the surface protocol, but about 20 seconds after surfacing, he started experiencing difficulty, and shortly thereafter lost consciousness. In terms of squeezes, this one was unusual in that little fluid was present initially, especially given the severity of the squeeze. Efforts by the doctor and paramedic at the scene to revive him were unsuccessful.

Later at the hospital, according to reports, approximately 800cc of fluid were removed from his lungs.


There has been some writing in the blogosphere about Nicholas's supposed obsession with numbers and records. While this may be true, I would submit that a lot of competitive freedivers are likewise obsessed. After all, when we are competing, we are competing against the other guy or gal and his or her numbers, yet we don't all die in our attempts. When Guillaume and William are thinking about CWT, I suspect they are probably thinking of a number at least 1 meter greater than the world record, yet no one says they are obsessed with numbers. I think the question is not just about obsessions.

I may be obsessed with a particular football team, but I would not shoot myself in the head to get tickets to a game. The correct question is, how far would I go to get the tickets, or for us freedivers,

How do I decide for myself when to turn early, or not dive at all?

How you answer becomes a matter of listening to your body, and when it is telling you to turn, you turn, to not dive, then don't dive. Be sure to pay attention. The bottom plate has no voice. To the extent possible, what to do should be thought of and practiced during your routine mental training, not when feel a sharp pain while you are narced at depth and your decision-making ability is compromised.

It is important, no matter how much you might want a particular depth, to accept the dive that your body gives you on a particular day. If that happens to get you to the bottom plate, great. If not, then so be it.

Nicholas had proven many times that he was willing to turn early, so I am not sure that the concept of obsession necessarily applies here. He had turned early in two previous CNF attempts to 72 meters already, yet it is possible that in an inordinate desire to get to the bottom plate, and in spite of the difficulties he was having on the dive, Nicholas ignored the limits of his body on that day and on that dive, and continued down to the bottom plate. No one can know for sure.

Still, I think it is more complicated than just saying his obsession with numbers and records caused his death, as there were other factors at play, which I discuss below.


I think the most important distinction to make here about the adaptation of your body and particularly your lungs to the stresses of freediving is that it appears to be discipline specific, and not necessarily always depth specific. The reason for this is that the motions (armstrokes, kicks, pulls) and stresses (particularly ascent stresses) involved in CWT are different from those of a FIM or CNF.

Nicholas had experience down to 100 meters when he set the USA record for CWT in May. He had been below his 72 meter CNF AP probably many times in both training and competition in the CWT and FIM disciplines. He did two 65 meter CNFs already in 2013 and went to 69 meters in CNF on 11 November - disqualified due to a pull. He did a perfectly clean 70 meter CNF in training just before the competition. I don't know how many times, if at all, he had done CNF to his target depth prior to his final attempt, but maybe his experience at deeper depths in CWT and FIM gave him an unwarranted confidence in his adaptation to the depth he was attempting in CNF, thus impacting his decision-making both before and during the dive.

His final CNF AP was 28 meters less than his record CWT. I might have felt confident to handle the depth given his experience. The only thing I can see that would indicate otherwise was the upper respiratory squeeze during his FIM attempt.

Ignoring the squeeze for the time being, the question that comes to my mind is this,

Does adaptation to a particular depth in CWT imply equal adaptation to the same or lesser depth in FIM or CNF?

A “No” answer to that question REQUIRES that a gradual approach to depth be done independently for each discipline.

Another question related to adaptation is whether freedivers are progressing too deep and too fast now. I have always been taught to progress in depth gradually. That said, how long that takes will always differ between individuals. In the end, it will always be up to the individual to determine if he or she is ready for a particular depth on a particular day. No one else has enough information to make the call.


To me, the big question here is not just the catastrophic damage from the final dive, but also the upper respiratory squeeze on his FIM attempt two days earlier. The squeeze may have appeared minor, but we will consider it anyway, as there is a lot we do not know about squeezes. It is not always easy to judge their severity. While I am certainly not the expert, if I had a squeeze two days before, I would have some serious concerns about attempting a big CNF, especially given the inherent difficulties and stresses involved in that event. The fact is that it is impossible for the tissues to heal from a squeeze in two days, so the question becomes this,

Can a squeeze cause damage that could be made worse, even fatally worse, if another deep dive is attempted too soon, thus making it possible that Nicholas died from damage that happened during his FIM and catastrophically ruptured during his final dive?


As this regards adaptation, I would submit that no degree of adaptation to depth will save you if your respiratory tract is too injured from a previous dive. It is possible that this first squeeze invalidated any assumptions Nicholas might have made regarding his ability to safely get to the depth he was attempting, thus he perhaps made the decision to dive and then to continue to the bottom plate based on flawed assumptions. Ordinarily you decide your AP based on your training and experience and what you know or think the other competitors are capable of. I think all of Nicholas's training and experience might have worked against him in this case, as they perhaps told him the dive was safe when it wasn't.

Another contributing cause of the squeeze during his final dive may have been tension induced when he briefly stopped above the bottom plate. To do that with the idea of continuing, he would not have been able to grab the line, so he may have made some kind of irregular motion to stop his descent that initiated the squeeze. He was probably struggling to equalize, so it is also possible he did something not visible on video, such as reverse packing, that might have caused the squeeze. It is possible he never felt any physical indication of the squeeze as the lungs have no pain receptors.

Perhaps some sort of protocol for dealing with and training about squeezes should be established, at the very least recommending a healing period and subsequent cautious return to depth after a squeeze, and mandating the process if the squeeze occurs during a competition. In the end, AIDA cannot control, predict, or through training completely prevent a squeeze during any particular dive, but in a competition setting, AIDA can control how we respond to a squeeze and recover from it.

Of note, in Dahab, Egypt at the first competition after Nicholas Mevoli's death, NPR reports in Some Competitors Say Free-Diving Needs a Safety Sea Change that "Maxim Iskander, a Canadian-Egyptian free-diver, withdrew . . . because of an injury known as a lung squeeze."

"How did I know? I spit a little bit of blood," Iskander says. "Not that much, but enough to tell you, OK, something happened." He expressed his caution this way, "I said to myself, 'I might as well rest and not make any stupid mistakes, especially considering what happened with Nick.'"

In the same competition, the "organizers asked divers not to compete if they had experienced a squeeze in the last month. They also limited the depth by which divers could attempt to exceed their personal record."


The main lessons I take from this are:

If your body speaks to you during a dive via things like sharp pains or unresolved ear issues, listen and make appropriate decisions without regard to the bottom plate. Also, go through these kinds of things during your training to ensure the decisions are more of a reflex action both before you dive to cancel the dive if needed and when you are at depth to turn when necessary.

It is important, no matter how much you might want a particular depth, to accept the dive that your body gives you on a particular day. If that happens to get you to the bottom plate, great. If not, then so be it.

Adaptation to depth in one discipline does not necessarily adapt you to the same depth in the others. Because of the different stresses involved in each discipline, particularly ascent stresses, it is necessary to gradually increase your depth for each discipline independently of the others.

Squeeze severity is difficult to judge, and squeeze damage could be cumulative, so it is important to fully heal from a serious squeeze before cautiously approaching depth again. A squeeze probably invalidates all your training and experience regarding safe depths on subsequent dives.

When you are diving and your body is under conditions of extreme compression and blood shift, it is important to ensure your actions do not unnecessarily exacerbate the stresses your lungs are experiencing.

You also have to be willing to NOT dive, as conditions or your physical state dictate.

So, what caused his death?

Probably some combination of following factors caused his death, and this involves some speculation on my part, as some of this can never be proven or disproved.

1. Obsession - wanted that particular bottom plate too much.

2. Adaptation - unwarranted confidence in his adaptation to the attempted depth.

3. Judgement and training -

Failure to recognize the significance of the squeeze during his FIM two days earlier, allow a proper period of healing, and then cautiously approach depth on subsequent dives.

During the dive failed to respond properly when he had problems at depth.

While experiencing difficulties equalizing, perhaps he did something that pushed him closer to a squeeze, such as reverse packing.

4. Tension - possibly induced when he stopped his descent, and more specifically by some sort of irregular motion he might have used to stop, or even just tension induced by the difficulties he was having equalizing.

5. Medical response - a doctor and paramedic provided care at the scene and were unable to revive him.

Scenario 1 (assumption – adaptation a factor, FIM squeeze not a factor)

Overconfidence in his depth adaptation for CNF impaired his judgment at depth. He stopped possibly due to ear issues, so once he resolved his ear problems, and thinking this depth was no problem for him, he continued to the bottom plate. When the final damage was done is unknown, but perhaps when he stopped above the bottom plate, or during the ascent when the stresses are the highest. In any event, he probably would not have felt any pain, as the lungs don't have pain receptors.

Scenario 2 (assumption – adaptation not a factor, FIM squeeze a factor)

The squeeze during his failed FIM two days earlier caused some kind of damage which weakened the capillaries in his lungs. For whatever reason, he either ignored or did not recognize the seriousness of the first squeeze, and dove in spite of it. After all, his previous training and experience told him that a 72 meter CNF AP was reasonable. During the dive, he was having a lot of difficulty, and stopped twice, but for some reason, he continued down to the bottom plate. At some point, his already weakened pulmonary capillaries failed catastrophically. It is probable though, that the damage was done without him ever feeling any physical indication of a problem, and nothing could have saved him once he decided to do the dive.

Scenario 3 (assumption – adaptation and FIM squeeze not a factor)

Everything was going just fine on the descent until he experienced equalization problems with his ears - Nicholas had a history of this. When he stopped his descent in order to recover his ears, he maybe reverse packed or made some other irregular motion that initiated a squeeze. He probably would not have felt any physical indication of this at the time, as the lungs cannot feel pain. He wanted this dive badly, so when he recovered his ears, he continued to the bottom plate, further increasing the damage. After the turn, the squeeze was possibly made even worse by the stresses of the ascent.

Scenario 4 (assumption – adaptation and FIM Squeeze both a factor)

Nicholas was not properly adapted to the depth he was attempting. He had tried the same depth unsuccessfully twice before in the previous week, so this depth was extreme for him. Even if he would ordinarily have been able to do the dive, the damage from the two day old squeeze compromised his adaptation to depth and made it impossible. At some point he possibly had ear issues, as he had a history of them, so he stopped his descent. Pretty deep, he was already past the limits of his already weakened lung tissue. At that point, some kind of stress from the stopping motion or other action such as reverse packing precipitated a squeeze. Nicholas wanted this dive so badly that after recovering his ears, and likely feeling no pain from the squeeze, he resumed his descent to the bottom plate, further exacerbating the injury. The stresses of the turn and ascent completed the ruin of his lungs.


Any of these scenarios is possible, as the relative contributions of all the factors involved are literally impossible to know, but in the end we can learn from this and take action to improve our thought processes, our training methods, and our competition rules in order to hopefully prevent a repeat of this tragedy in the future.

Medical Response

A doctor and paramedic should have been more than sufficient to handle any problem, especially considering the range and severity of problems experienced in the long history of AIDA competitions. In fact, no one had ever died in an AIDA competition.

A lot of times though, things like this happen partly because of a failure of imagination – failure to imagine the crisis that ultimately happened, and to be prepared for it. An example of this is the seawalls protecting the Fukushima reactors – the tsunami wave was taller than the seawalls, so the designers failed to imagine the tsunami that ultimately occurred, and design the seawalls to protect the plant from it. Is it possible that this particular medical tsunami wave was taller than we ever imagined, or that somehow we had become complacent concerning the real risks we face when we dive? The whole safety team was top notch, and I am sure everyone did their best to save his life. In the end, however, Nicholas may have been beyond saving, but the question must still be asked and answered – was the medical care adequate to the situation at hand? If the answer is no, then are there changes we can make, short of transplanting a trauma care facility to the dive platform, that will improve the situation and hopefully minimize the risk of another similar tragedy?

One thing we must remember though. Even after we fix any problems we find, as long as we accept freediving and doing competitions in remote locations, access to emergency care will necessarily be limited. While doing everything we can ensure that the sport is as safe as possible, there are still risks involved, and we each knowingly accept them.

As far as what more could have been done in this case, I don't know enough to even speculate, so I will wait with the rest of you for the results of the investigation, which I am sure will go into this.


Blood Shift and Lung Squeeze:

From the time the freediver commences the breath-hold at the surface, peripheral vasoconstriction acts to move blood from the extremities into the organs in the thoracic region, beginning the blood shift. Vasoconstriction is further enhanced when the face is immersed.

As the freediver submerges and depth increases, water pressure also increases, causing the chest and diaphragm to be compressed inward. At some point, the limits of chest compression and diaphragm flexibility are reached. As depth continues to increase, the water pressure on the extremities along with peripheral vasoconstriction cause a higher pressure in the peripheral blood supply than exists in the chest. This pushes blood from the extremities into the thoracic organs.

Much of this additional blood in the thorax goes into the lungs and into the pulmonary capillaries in the alveoli walls. This causes the capillaries to expand and compress the intra-alveolar gases. Intra-alveolar gas pressure, overall lung gas pressure, and therefore overall pressure inside the chest all increase as a result. The pressure increase inside the chest opposes water pressure on the outside of the chest, and is what prevents the chest from being crushed on deep dives.

It is an oversimplification to talk about the lungs being compressed to the size of apples, or grapes, or whatever, as once the limits of chest compression and diaphragm flexibility are reached during the descent, the lungs do not actually shrink much more. The limits of chest compression and diaphragm flexibility prevent it. Probably if the whole lungs were squashed to the size of apples, blood flow in the lungs would be squashed as well. Contrarily, blood shift relieves some of the pressure on the chest while still allowing adequate blood flow through the lungs and heart.

Blood shift continues with increasing depth, and is what has made it possible for freedivers to achieve such great depths. This process relies ultimately on the elasticity of the capillary walls in the alveoli. The limiting factor ends up not being water pressure pushing on the chest, as this is nicely handled by the blood shift, but rather the pressure difference between the alveoli blood supply and the intra-alveolar gases.

Lung squeeze occurs when at some point the capillary walls are stretched past their elasticity limit and start to burst. Blood enters the air spaces of the lungs (pulmonary edema), and we see it when the freediver spits up blood at the surface. It is possible that, in addition to the depth itself, irregular motions and turns might precipitate this kind of squeeze. I suspect that along with depth, anything that might introduce unbalanced stresses in the chest and lungs might increase the likelihood of a squeeze.

Movements that reduce intra-alveolar gas pressure might increase the probability of a squeeze as well. Putting the arms overhead or pushing the diaphragm toward the pelvis could do this. These motions perhaps slightly increase lung volume and reduce intra-alveolar gas pressure relative to pulmonary capillary pressure, sending the pulmonary capillaries closer to their bursting point. Reverse packing would have a similar effect. While not increasing lung volume as the other motions above, this practice reduces intra-alveolar gas pressure by forcefully withdrawing air from the lungs.

Anything that increases blood pressure generally or raises pulse rate might also be a factor. Every time the heart beats, it sends a pressure spike downstream through the pulmonary arteries and capillaries.

Lung squeeze is not a trivial matter. In addition to the visible blood, lung squeeze can in serious cases cause difficulty breathing, reduction in arterial oxygen Saturation, unconsciousness, and death.

Figure 4, page 288 of “The physiology and pathophysiology of human breath-hold divers” is an excellent illustration and explanation of blood shift and lung squeeze.

Trachea Squeeze:

A trachea squeeze occurs when water pressure compresses the cartilage in the trachea and eventually causes damage and bleeding into the upper respiratory tract. Again, blood at the surface. Particular motions with the head and neck can precipitate a trachea squeeze.

Adaptation (particularly as it relates to the chest, diaphragm, and lungs):

Physical adaptation of the chest, diaphragm, and lungs is all about flexibility, or maybe more properly chest compressibility with diaphragm and pulmonary capillary stretchability. As the freediver continues to train and gradually increase depth, the chest, diaphragm, and pulmonary capillaries are stressed. This improves flexibility, but go too deep too fast, and things get broken, particularly the pulmonary capillaries, so it is important to gradually increase depth in order to improve flexibility without causing tissue damage.

Some things might compromise adaptation on a particular dive. Illness and stress are two examples. Injury is another. Lung and chest injuries particularly reduce flexibility and therefore your adaptation to depth. Particular care is necessary when freediving with any injury, and it is probably never advisable to freedive with an unhealed lung injury. Even after a lung injury is healed, it is wise to return to depth cautiously.

I would thus further define adaptation(A) as unique to each discipline and also unique to each dive, and affected by environmental, physical, and mental factors such as water temperature, illness, injury, and stress, with ACNF being different from ACNF-coldwater or ACNF-head cold or ACNF-previous squeeze or ACNF-chest injury or ACNF-fight with spouse. The concept of adaptation being a constantly moving target requires constant self-evalutation - “Am I safe to dive this depth today?” Honest answers to this question will sometimes require us to cancel dives or lower our expectations. However disappointing that might be, our lives depend on it.

Note: See the summary of the autopsy reports by Dr. Per Vestin in the references below.

Author: Walter L. Johnson I am a 57 year old freediver, living and training in Phuket, Thailand. In a prior life, I spent 21 years operating and repairing nuclear reactors, steam plants, and their systems. My expertise was in management, nuclear physics, thermodynamics, fluid flow, mechanical systems, chemistry, health physics, computer programming, and counseling.

First published on December 13, 2013
Revised on December 18 and 28, 2013, January 9. 2015, 12 April 2015, and 22 February 2016


Kathryn McPhee Nevatt, Lung Squeeze Clarified, Kathryn McPhee Nevatt, 30 November 2009.
Mayo Clinic Staff, Pulmonary Edema, Mayo Clinic, 24 July 2014.
Wikipedia contributors, Mammalian diving reflex, Wikipedia, The Free Encyclopedia, Last revision: 4 April 2015.
Charles Lane, Some Competitors Say Free-Diving Needs a Safety Sea Change, NPR News, 17 December 2013.
Peter Lindholm and Claes EG Lundgren, The physiology and pathophysiology of human breath-hold divingJournal of Applied Physiology, vol. 106, no. 1, pp. 284-292, 1 January 2009. Walter L Johnson, The Ability-Adaptation Squeeze Model, freedivingsolutions.com, 26 December 2013.
Dr. Per Vestin, Official Summary of the Autopsy Reports Following the Death of Nicholas Mevoli, AIDA International, December 2015