Freediving, Embodiment and Humanity

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In this post I'd like to utilize my experience with freediving as an excuse to talk about a bunch of seemingly contrasting qualities and emotions, which together — I feel — illustrate some deeper aspects of experiencing humanity. For me, at least, freediving has turned out a surprisingly useful tool in this endeavor.<br>Freediving is a curious activity. You take a deep breath and off you go — a few tens of meters under water: 30, 40, 50m, maybe more if you're really good. Or maybe just 20m deep, but for a more relaxed fundive, enjoying flying in 3D space among rocks, coral reef or wrecks. We don't need all those clunky tanks with air or other gases, which scuba divers are so dependent upon. And, unlike scuba diving, we're not limited by ascent rates, meaning we can travel vertically as fast as our fins (or scooter!) let us do that. We dive silently without exhaling bubbles and without those Vader-like breathing noises, so marine animals are not scared of us. We're sleek and free. Unified with the environment and ourselves. Pure freedom.<br>Urge To Breathe<br>But there's a catch. Breathing is our most primordial reflex. Try holding your breath now — start your stopwatch and see how long it takes for you to feel the first symptoms of what we call Urge To Breathe (UTB)?<br>Now imagine you are forced to remain breathless for another minute or two, or more... How would you describe the feeling?<br>The UTB sensation can typically be reduced to a few more basic symptoms: contractions of the diaphragm, sensation of heat, feeling of pressure on the chest, urge to swallow, or feeling of pressure on our glottis. These elemental symptoms are interpreted by our brain's higher-level subsystem(s) as a pressing need to resume breathing.<br>Interestingly, when we learn to "decompose" this high-level feeling into the more basic bodily reactions, UTB usually gets a bit easier to tolerate. At least for a bit. My understanding of this phenomenon is that our brain is alerted by these bodily reactions, rather than directly by the CO₂ sensors. This is perhaps similar to how a bit of liquid on our cheeks might make us feel sad, because our brain thinks we're crying. But once we understand the liquid comes from the eyedrops, not our tears, the feeling of sadness vanishes.<br>Nevertheless, the longer we push beyond the first UTB symptoms, the more difficult it is to tolerate the situation. Suffering starts spreading all over the mind…<br>While cells go about their whatever-they-are jobs, they burn oxygen (O₂) and produce carbon dioxide (CO₂) as a side product. CO₂ is then collected by blood, transported back to lungs and expunged when we exhale. And, quite surprisingly, we are actually sensitive to the buildup of CO₂ level in our organism, rather than the dropping level of oxygen. Interestingly, in most humans1, the critical CO₂ threshold that triggers UTB symptoms comes very early, much before the oxygen level falls into the dangerous territory.2<br>Our nervous systems are very conservative, in other words. If you are a generally healthy individual and have a pulse oximeter nearby, you can make an interesting experiment. Sit comfortably, put the oximeter on your index finger, then inhale and hold your breath. Keep holding it until you start feeling the first symptoms of an urge to breathe. At this moment notice the oxygen saturation (and resume breathing).3<br>In most healthy humans, the oxygen saturation will still be at a very high level, above 95% say. This means there is still a lot of oxygen in your blood. And yet, since you already started feeling the UTB symptoms, your nervous system already thought it appropriate to trigger an alarm to resume the breathing.<br>How nice would it be to "hack" one's own autonomous nervous system so that it was a bit less anxious…<br>I already hinted at one technique that might be useful — consciously focusing on what we feel in the body. Others exist. In general they fall into — or can be applied — in two broad approaches. One is through suffering, while the other through finding bliss and pleasure in the act of freediving. We will get back to this in a moment.<br>For now, I will just note that there is an obvious tension here between a desire to stay underwater longer (because it feels good) on the one hand, and the desire to resume breathing (because it feels bad once we move past the first symptoms of a UTB).<br>Pressure And Equalization<br>But breath holding is, surprisingly, not the only challenge in freediving. In fact, as far as depth diving4 is considered, the breath hold times are typically not the prime limiting factor. At least not at the beginning of one's journey…<br>When we dive deep, many tens of meters underwater, the pressure of the surrounding water rises very quickly. For every 10 meters of depth we get another 1 bar of pressure (or 1 atm). This means that at 40m (130 feet) the surrounding pressure is 5 times of what we experience on the surface. How is it that this...