Halfway through my intern year, I hung up my white coat for a week and flew to Grenada for a sailing expedition with four friends. We boarded our two-sailboat armada and headed for Ronde, an island about four miles north of Grenada, where the live reef made for spectacular free diving.

In the months before the trip, I’d tried to whip myself into shape. At the gym, I’d practiced what I figured were the free diving necessities: holding my breath and swimming. I’d downloaded Apnea Trainer, an app that helps you improve your breathing technique. My wife bought me a smartwatch to count the number of laps I swam.

But the first day in Grenada, I realized my training hadn’t been enough. I strapped on my fins and dive knife, goggles and snorkel and descended. I hovered at about 10 meters with my timer ticking. The filtered light cast shadows on the alien environment. The cool water forced a tinge of unease over my skin. I kept my eyes peeled for a hungry barracuda as curious fish swam by me, apparently unimpressed. 

Less than a minute into my dive, the blood began to pound in my head and my diaphragm began to twitch. I surfaced. A bit frustrated (and embarrassed), I wondered what had gone wrong—hadn’t I trained for this?

That night over beers, I whined that my swimming and breath-holding training hadn’t made me into the expert free diver I’d imagined. “It takes a lot of practice,” my buddies assured me, “you’ll get the hang of it.” 

As the week went on, my dives did indeed improve—I dove deeper and for longer amounts of time, as if I had grown stronger muscles or larger lungs. But that didn’t add up: muscles and lungs don’t change much in one week. So what had changed? Tracking down the answer exposed me as a closet dualist and led to a renewed respect for the depths of the brain. 

FREE DIVING CONSULTS

A few months after my Grenada trip, I sent an S.O.S. to the Association Internationale pour le Dévelopement de l'Apnée (AIDA; in English, the International Association for Development of Apnea), hoping to learn more about the free diving training process. Felice Mastroleo, who heads A.I.D.A.’s Education Committee, responded. 

Mastroleo is a scientist-adventurer who began free diving off the coast of his native Italy. A part-time free diving instructor, when he isn’t donning a wetsuit, he studies how bacteria survive on the International Space Station. Over Skype (I was in Vancouver, he in Brussels), I explained my first lackluster dive, how I’d improved over the week, and I asked him how he teaches his students.
  
“It’s all about breathing. A lot of time students only breathe with the chest, which is not very deeply. I teach them two-step breathing: first the belly, then the chest. Focus on the exhale to decrease your heartrate.... I go straight into the water after this.”

I’d done breathing exercises with my Apnea Trainer app, but the way Mastroleo described the process (“focus on the exhale to decrease your heart rate”) suggested an additional, mental layer to the exercise. I mentioned that this sounded an awful lot like the mindfulness training I teach my patients, the breathe-in-and-slowly-out, in-and-slowly-out. He chuckled, “I guess so.” 

Being relaxed, he told me, was key to a successful dive. And he deliberately cultivates this emotion in his students, : “the first thing is the way you talk to students. You have to be more relaxed than them. You’ve got to be relaxed yourself.” 

That Mastroleo’s first lesson focused on calm breathing, that his persona was decidedly relaxed surprised me. If our Grenada trip had a theme song, it would have been a Stan Rogers sea chantey or AC/DC’s “Thunderstruck”; Mastroleo wanted “Claire de Lune. 

We spoke for over an hour. He regaled me with his exploits (he’d recently returned from Croatia) and his scientific research. I was curious how other instructors prepared their free divers, so Mastroleo suggested I phone his mentor, the Sardinian free diver Umberto Pelizzari.

Pelizzari is a two-time A.I.D.A. world champion and, according to some, one of the best free divers of all time. Pelizzari—and his rivalry with his old friend, Cuban free diving champion Francisco Ferreras—was the subject of the recent 2001 IMAX documentary Ocean Men: Extreme Dive. (Film junkies: you might also be interested in Pelizzari’s diving mentor, Jacques Mayol, whose own rivalry with Italian diver Enzo Maiorca was captured in another movie cult classic, The Big Blue.) 

Pelizzari has written extensively on free diving and travels the world teaching on-site lessons to those with deep courage and deep pockets. As he is a fiercely competitive free diver, I expected Pelizzari to give me a rigorous training regimen: 1) ten-kilometer swim before breakfast; 2) hold breath five minutes every hour; 3) seaweed and fig diet; etcetera. So when I asked him what he recommends, I was surprised when he quickly said, “Oh, free diving is very mental, it’s not technical. The first step isn’t training. You have to eliminate the natural mistakes we make in the water.”

Before zipping up a wetsuit, Pelizzari has his students splash around in the water. He wants them to move naturally, to gain an intuitive comfort in the water. Only once someone is comfortable, does Pelizzari begin specific, simple exercises like fluid kicks, first without then with fins. 

A scene in Ocean Men shows Pelizzari practicing Pranayama yoga, a meditative technique that focuses on breathing. He helps his students master their breathing. “I also ask people to imagine a concert or a relaxing song to help busy the mind.” Pelizzari considered these mental calisthenics as important to free diving as proper kicking, helping people feel that they can exist in a place where they are—at best—touristas

As I would learn, this focus on mental training, on feelings isn’t because free diving attracts neurotic swimmers. It’s purely physiological. 

MINDFULNESS—OR BRAINFULNESS?

Not long after I spoke with Mastroleo and Pelizzari, I got a phone call from Dr. Blaise Aguirre. For the last 10 years, Aguirre has been the Medical Director of 3East at Harvard-affiliated McLean Hospital. He’d called to chat about a piece I’d written for Scientific American that questions the language we use to discuss emotion. Aguirre had just returned from a one one-month whirlwind tour of South America, Africa, and Europe, where he had lectured about mindfulness training in understanding and controlling one’s emotions, something he has written multiple books and articles about. He seemed like the perfect guy to ask.

So I recounted my free diving experience and what I’d learned about breath control and mindfulness from Mastroleo and Pelizzari, curious what Aguirre would add. 

He explained that there are many forms of mindfulness; one form might be focusing on the tip of your nose, breath, or kicks in free diving. By imagining a concert or relaxing place, Aguirre explained that Pelizzari had used a cognitive behavioral therapy (CBT) technique called distraction.

An example of distraction is an insomnia remedy used by the German philosopher Immanuel Kant, as described in his very-Kantian-titled book section On the Power of the Human Mind to Master Its Morbid Feelings Merely by a Firm Resolution

....impatient at feeling my sleep interfered with, I soon had recourse to my Stoic remedy of fixing my thought forcibly on some neutral object that I chose at random (for example, the name Cicero, which contains many associated ideas), and so diverting my attention from that sensation. The result was that the sensation was dulled, even quickly so, and outweighed by drowsiness…. I can repeat this procedure with equally good results every time....

Kant’s method has clinical utility (and I confess the image of Kant, the demigod of “Pure Reason”, squirming in bed at two 2 A.M. made me smile with Schadenfreude). In a study of 76 patients with clinical depression, distraction techniques helped turn the tide of negative mood. It appears that making a habit of refocusing attention to a neutral topic improves mood, allowing patients to press through pesky, ruminative moments. 

The implication of these German experiments is that thoughts—whether positive, negative, or neutral—are a brain process that, like any procedure, requires effort. By engaging the brain’s machinery in a neutral task “Cicero, Cicero, Cicero” we swap our attention sets, re-allocating our neural processors. 

Speaking with Aguirre, it finally occurred to me that I’d considered “free diving fitness” through the lens of mind-body dualism. During my training, I’d focused only on the physical fitness of my muscles and lungs, without giving much mind to what my brain was busy doing 10 meters below the surface. 

During a dive, the brain detects distress signals—carbon dioxide levels increase in your blood and are sensed by chemoreceptors in your carotid arteries; the water pressure increases by one atmosphere every 10 meters you dive; the emotions of being in a foreign, deadly environment—these signals engage your sympathetic nervous system. When this happens, your heart speeds up, metabolism increases and you burn through your oxygen reserves faster. So the distraction techniques, the breathing exercises, the deliberate, “mindful” calm that Mastroleo and Pellizzari described weren’t some monastic abstraction, but the nuts-and-bolts of neurobiology. 

Aguirre was keen to remind me that “it’s all biology at the end of the day … different [mindfulness] practices target different neural circuits, so you can play around with them.” As I’m a student of clinical neuroscience, the “it’s all biology” assertion stuck with me. 

So my problem that first day in Grenada was that as I hovered motionless at 10 meters, my brain buzzed with anxieties: “What if a barracuda bites off my arm? What if I get lost underwater?” No wonder my heart was pounding—I’d worked myself into a sympathetic frenzy. As the week went on, I calmed down and became more mindful of what I was doing. With less on my brain, I could spend my energy exploring the reef’s nooks and crags.

Keeping your cool underwater (especially on an AIDA level) takes practice, which is why after countless dives, Pelizzari runs, swims, and meditates before a descent: the adventure requires brawn and brain.