When I tell people that I freedive, after we’ve established the fact that, no, that does not mean scuba, I get one of two reactions: ‘How long can you hold your breath?’ or ‘That’s so dangerous’. I cannot count the times that these, frankly largely irrelevant and downright incorrect, misconceptions are voiced, and it only serves to show the depth of ignorance that surrounds the discipline. No wonder—it is a niche sport and community.
Hopefully this article can address some of the major misconceptions, and cover the basics of what actually does happen to the body at depth. In short, what are we actually doing down there? And perhaps more to the point, why?
For less technical description of freediving check out: Embrace of the Deep | Diving to 40m below
Freediving is a transformational discipline. Both technical and intangible, it demands an absolute control of the body and its functions. Perhaps most remarkable are the mental demands of breath-hold diving: conscious control of our deepest human instinct – the urge to breathe. To suppress such an instinct requires a combination of psychological conditioning, emotional control and meditative willpower.
As is pretty typical, I came to freediving with a very limited understanding of how it worked and how to train it. Everything I knew I’d read online. Some of this was correct – most of it was, although not strictly wrong, vastly missing the point.
There are many misconceptions about the technicalities of freediving, and these are only magnified by the lack of material aimed at explaining the intricacies of apnea diving to non-divers. It’s an extremely technical discipline, demanding a vast degree of physiological control and understanding – even amongst freedivers there is misinformation and ignorance, not helped by the scarcity of concrete academic research in this rapidly expanding but still relatively new sport.
But I think perhaps the largest cause for misunderstanding is the assumption that freediving can be compared directly to other physical disciplines. This was my approach, coming from a background of running, swimming and climbing. Yet freediving is an altogether different concept, based around a reversal of values. To try harder in freediving is to go backwards: to push yourself is to fail.
I wrote this article to dispel some of the misconceptions I held before I began freediving, and open eyes to the realities of this unique discipline. The world of freediving requires an entirely different approach to that of other sports, yet, for me it least, the insights and perspective I learnt underwater have been invaluable in training other disciplines.
1) It’s all about the breath-hold
2) It’s not that physical and so it’s not that tiring
3) Difficulty and improvement are linear with depth
4) Freedive training is about aggressively pushing limits
5) Freediving is extremely dangerous
For a more descriptive account of freediving and its allure check out:
Or this video I put together:
A World Below | Freediving in Bali
It’s all about the breath-hold
Understandably, just as I thought when I started, most people assume that what limits the depth of a dive is how long you can hold your breath. This isn’t helped by the fact that the majority of literature and instructional articles out there are based around increasing the breath-hold.
Admittedly, for the elites of the discipline, the breath-hold is the limiting factor. Yet for those of us that aren’t diving to elite depths, we just aren’t underwater for that long. The deepest dives I’ve personally managed – just over 40m and a couple of minutes downtime at most – barely push me in terms of air. Instead other factors get in the way.
A friend of mine once described it as triangle of issues that had to be overcome to go deeper. As soon as one has been addressed, another rears its ugly head and becomes the limiting factor, and this cycle continues as you progressed deeper, each one reappearing again and again in turn.
The three factors are: equalisation, pressure, and relaxation.
As we go deeper, the air in our eustachian tubes (the tube towards the middle ear) is compressed under pressure, and more air needs to be forced into the cavity to prevent the ear drum from bursting. Anyone who’s gone more than a meter or two underwater will have felt the pinch.
Initially, assuming you have some idea what you’re doing, equalisation is fairly straightforward – the correct technique of using the tongue to compress the soft-palette (the frenzel manoeuvre) is quickly learnt if it isn’t already instinctive. But, as you go deeper the negative pressure in your shrinking lungs makes the procedure more difficult and soon bringing up more air becomes impossible. The solution is to bring up a mouthful of air before this point and periodically use it to equalise through a chosen combination of pulses or constant-pressure from tongue and/or cheeks.
But with the ever-decreasing pressure in our lungs, keeping the glottis shut and preventing our mouthfill from disappearing back from whence it came can be extremely difficult. This is particularly true when upside down, trying to concentrate on staying relaxed, negotiating the intricacies of tongue-to-soft-palette control and freefalling into darkness. If the air leaks down the throat or is swallowed, the dive is over.
At each new depth equalisation is a new game to master, whether due to the specifics of keeping a mouthfill, or simply working out which specific combinations of tongue position seems to work best. It’s very individual, and just knowing which muscles you’re using and what exactly you’re doing in each moment can be extremely challenging!
The next factor is water pressure. As we descend, an atmosphere of pressure is piled on every 10m, meaning that compared to the surface, at 30m one would experience four times the pressure on the surface. Our lungs are compressed to a quarter of their original size.
You feel this when freediving – the weight of the water pressing in on you, crushing your body. It isn’t altogether unpleasant, but the dangers it entails should you push further than you’re ready for are very real, and coughing up blood due to tiny collapses of the lung (lung squeeze) or upper airway (trachea squeeze) is not uncommon in amateur freediving – I’ve seen it many times.
To deal with the pressure freedivers must increase their tolerance through stretching and strengthening their lung and connective tissue, and ensuring their body positioning at depth is correct. This conditioning can be achieved by diving a lot (and the speed of tolerance increase can be rapid – I remember going from feeling crushed at 30m to diving comfortably and loose to 40m in less than three weeks), various lung stretching exercises (Uddiyana Bandha being the key one) and if experienced enough, dives on exhale to simulate higher pressures at less depth.
This is the big one. Oftentimes issues of pressure tolerance and equalisation are simply the result of tenseness in the body: physical manifestations of an unrelaxed mental state. The difficult part is realising this. Yet however tension manifests, whether in equalisation, pressure-intensity, a feeling of lacking air, or simply a mental distraction and even panic, it has to be overcome and dealt with over and over again as each new depth is made comfortable and familiar.
It is notable that as a diver goes deeper, pressure increase becomes slower: 33% from 20-30m; 25% from 30-40m. By the time we reach 90-100m, the pressure increase is a negligible 10%. As a result – though in the interest of full disclosure, I’ve never actually been there… – the issues of pressure tolerance and equalisation gradually become less pressing. On the other hand, relaxation becomes even more important, and the breath-hold soon enters play as a limiting factor.
It’s not that physical and so it’s not that tiring
There’s no doubt that a session of line training is not particularly physical. Whilst you may tire your legs a bit in the lactic acid of anaerobic kicking, in relation to the physical demands of ultrarunning or rockclimbing there’s no comparison: freediving is dependent on relaxation, not exertion. I figured this meant that I could continue to train running and strength alongside my diving as it wouldn’t need much recovery. I couldn’t have been more wrong.
I’m no stranger to being truly tired. Training for ultramarathons in the past I’ve literally run myself into the ground on more than one occasion, or laid awake at night unable to sleep for the dull, neurological beyond-muscle ache in my legs after back-to-back marathon training runs: I know what it is to be physically exhausted. But the exhaustion you feel from freedive training is unlike anything else: it’s just different.
A long session of 4 hours diving at your limits will leave you barely able to keep your head up for the rest of the day, let alone go running. I’m not a hundred percent sure exactly why this is, but I think it’s due to the effect freediving has on the nervous system. For those of you that are climbers, I can only compare the fatigue to the neurological weariness after an intense hangboarding session: physically you feel little, but your energy is simply gone.
Freediving is extremely neurologically draining for a number of reasons. Operating under breath-hold is definitely nervously-strenuous, and perhaps also the pressure that comes with depth. Certainly it is likely that the consequent autonomic coordination of the extreme physiological responses entailed by the mammalian dive response: brachycardia, blood shift, splenic contraction, and peripheral vasoconstriction, also constitute a drain on nervous energy.
The psychological demands of staying present and absolute concentration on the moment would be a further load on the nervous system. Suppressing the urge to breath and staying calm in an environment that our body is instinctively wired to fear must also be a huge neurological drain, however subconscious these thoughts may be.
I remember reading an article, in reference to what discipline I cannot remember – I think maybe strength training – , about how, unlike muscular output, the nervous system has a finite energy reserve, and that the recovery of said reserve takes much longer (in the region of days) than the 3-5 minutes of ATP regeneration in the muscles. You feel this more than anything with freediving – once a point is reached and your reserves are gone, it’s session over. This concept also helps to explains why, when emotionally drained for whatever reason, your freediving suffers.
In short: Recovery in freediving is of paramount importance – it’s very easy to overtrain.
Difficulty and improvement are linear with depth
For anyone who’s given freediving a good go, it becomes clear pretty quickly that the difficulty of diving does not increase logically as you get deeper. Unfortunately, because of the technicalities described above this just isn’t the case.
My improvement in freediving makes this immediately obvious. I was very comfortable in water (thanks to a childhood of ploughing a pool) and equalisation came easy. I progressed fast and reached 25-30m in less than a week – this isn’t uncommon. But it then took me more than a month to go another 10. This appears to be a pretty typical progression pattern. As with anything new, the improvement curve begins steep and then plateaus. Yet in freediving it’s even more intense.
Past 30m we hit what is called residual volume, or RV. At this point our full lungs are compressed to the equivalent volume they’d be if we were to force out as much air as possible when standing on land: ~20-25% of total lung capacity. Typically you get a strong sensation of lack of air and even with practise this region of the dive can be disconcerting before we relax fully into the crushing feeling beyond.
RV also causes technical problems. At this point air cannot (easily) be brought up from the lungs, and so the ability to equalise now rests on keeping hold of the air already in our mouth. For me it took some time to work out what I was doing and not hit an equalisation wall every time I reached ~35m.
Another possible reason for non-linear improvement might be that so much of freediving is mental. And mental breakthroughs don’t tend to come incrementally in the same way that physical conditioning improves. Instead, improvement in freediving often takes the form of long plateaus and sudden breakthroughs, where a key aspect of technical understanding or an abstract realisation of self-awareness removes the mental and physically-manifested blockages to performance. Suddenly we shoot forward 5m in a matter of days, before getting stuck again soon after.
Much of freediving improvement is below the surface: invisible forward motion that is realised in staggered performance improvements.
Freedive training is about aggressively pushing limits
Training freediving requires a unique approach. Freediving is based in relaxation, and so the very concept of ‘trying’ is counterproductive. Coming from a background of gutting out the miles in ultramarathons or straining every muscle to hold onto a wall, I found this a hard one to adapt to.
Trying hard has its place in freediving – in commitment, positivity and the odd lactic pool session – but for the most part the harder you push, the harder it becomes. A spiral of frustration and lack of progress is born. I found it extremely frustrating, and, if I’m honest, I did at times crave the bloody-minded focus and willpower of pushing myself beyond limits and pain-thresholds. But freediving is unequivocally not the place for such masochistic vulgarities.
In fact, the manner in which we push our limits is different in freediving altogether. In most disciplines you make an all-out effort to reach a new level, and then from there you strive to make it comfortable, thus improving. In freediving it’s reversed. One must make the new level comfortable first through thorough preparation, and only then glide effortlessly to new heights (or depths…). This went against all the motivational quotes I’d ever read – stepping out of your comfort zone was not the solution. Rather, the region beyond must be made your comfort zone before you even go there.
Why? It’s because pushing too hard leads to regression in a far more aggressive manner than in other sports. In freediving, injury can come suddenly and unexpectedly, like the dreaded blood-cough after a loose arm movement at PB depth. I’ve seen squeezes from just that – even at less than PB.
Perhaps even more detrimental than an injury-forced dry-spell however, is the mental damage caused by negative experiences. Freediving is so psychological, that an uncomfortable dive beyond your comfort zone can cause a powerful mental block that prevents further progress. And unlike physical issues, it can be difficult to work out how to cure it. Essentially, an uncomfortable dive is backwards training, and arguably more damaging than a good dive is beneficial.
Freediving is extremely dangerous
How many times have I been asked about the risk? ‘Have you seen the Big Blue’? The familiar condemnation is something every freediver has to deal with. This is the big one – it had to be included. I’ll keep it brief.
Freediving can be dangerous – if done irresponsibly. And I’m not going to go into the obvious and dull discussions of ‘always dive with a buddy’, ‘know what you’re doing’, ‘don’t hyperventilate’ and so on. Rather, it’s a common misconception that freediving is dangerous because of the risk of running out of air and drowning. To address this I want to quickly describe the major dangers of freediving and how real these risks actually are.
(i.e. running out of air and, potentially, drowning)
The obvious one. In reality, for amateur divers diving sensibly this is extremely unlikely. As mentioned earlier, breath-hold is hardly the limiting factor for beginner freedivers, and so the risks of running out of air and blackout are minimal.
In the very rare case that blackout does happen, it’s usually on (or very close to) the surface (as an effect of lowered pO2 at the point of exhale) and your safety diver will be able to bring you round almost immediately – so far no long-term effects have been identified.
In terms of fatalities, of the 50,000 dives of AIDA competitive freediving, there has been only a single recorded death. This statistic is significantly higher in recreational diving (including spearfishing and non-line diving) at ~1 in 500. However, it’s probably fair to say that this is largely the result of irresponsible diving, or overzealous spearfishing – likely also the origin of the unnerving statistic that 75% of freediving accidents end in death.
As the AIDA statistics attest, if diving is done in a controlled and safety-conscious manner, blackout should result in safe and simple recovery.
Again, pretty unlikely. You’ll usually feel pressure on the eardrums long before they burst, and turn around to avoid any damage. In the rare case that it does happen, these heal with time out of the water.
These are perhaps the most real risk in freediving: small collapses of lung alveoli, or capillary bursts in the trachea. These are caused by pressure at depth and are fairly common in training. Though I’ve never had one, I’ve seen plenty. In all truth, there is no reason why these should ever happen if personal bests are pursued slowly enough, but understandably people get ahead of themselves. When it does happen, its usually just a case of resting for a month or so before it heals up.
You don’t want stacks of them because of the inflexible scar tissue they create in the lungs (which in reality probably only affects freediving), but a few won’t hurt you – they’re just inconvenient.
Very rare in amateur freediving, the risk of decompression sickness is basically down to three factors. 1) Regularly diving to extreme depths with little rest (we’re talking 80-90m plus). 2) Mixing freediving and scuba – in which case I’m inclined to blame the scuba. 3) Repetitive diving without a sufficient surface interval. In line diving the last is hard to achieve at amateur depths since you’ll be alternating with a buddy – in any case it’ easy to control. It’s in spearfishing that this is a more likely situation, where rapid surfacing and re-diving become necessary to pursue a fish. Decompression sickness is a nasty business – don’t go there.
Get in touch if you have any questions or comments – it'd be great to hear from you.