Mastering the “Master Switch”

Mastering the “Master Switch”

In 1949, a stocky Italian air force lieutenant named Raimondo Bucher decided to try a potentially deadly stunt in a lake on the island of Capri. Bucher would sail out to the center of the lake, take a breath, and go down 100 feet to the bottom. Waiting there would be a man in a diving suit. Bucher would hand the diver a package, then kick back up to the surface. If he completed the dive, he’d win a 50,000-lira bet; if he didn’t, he would drown.

Scientists warned Bucher that the dive would kill him. An equation called Boyles Law indicated that the pressure at a hundred feet would shrink Bucher’s lungs to the point of collapse. He dove anyway, delivered the package, and returned to the surface smiling, with his lungs perfectly intact.

Bucher’s dive resonated with a long line of experiments that seemed to indicate water might have life-lengthening effects. More than 50 years earlier, experiments found that immersion in water allowed animals to survive up to three times longer without oxygen.

Then in 1962, Per Scholander, a Swedish-born researcher working in the United States, examined the effect of water on humans. He led volunteers into an enormous water tank and monitored their heart rates as they dove down to the bottom. Just as it had done with animals in earlier experiments, water triggered an immediate decrease in heart rate.

Next, Scholander told the volunteers to hold their breath, dive down, and do a short, vigorous workout. In all cases, no matter how hard the volunteers exercised, their heart rates still plummeted.

Scholander noticed something else: Once his volunteers were underwater, the blood in their bodies began flooding away from their limbs and toward their vital organs. He’d seen the same thing happen in deep-diving seals decades earlier; by shunting blood away from less important areas of the body, the seals were able to keep organs like the brain and heart oxygenated longer, extending the amount of time they could stay submerged. Immersion in water triggered the same mechanism in humans.

Scholander found that a person need submerge only his face in water to activate these life-lengthening (and lifesaving) reflexes. Other researchers tried sticking a hand or a leg in water, to no avail. As it turns out, the tradition of splashing cold water on your face isn’t just an empty ritual; it provokes a physical change within us.

Scholander had documented one of the most extreme transformations ever discovered in the human body, a change that occurred only in water. He called it the Master Switch of Life. Today, competitive freedivers are using the Master Switch to dive deeper and stay underwater longer than even modern scientists believe should be possible.

On September 17, 2011, I traveled to Kalamata, Greece, to watch modern-day masters of the Master Switch—100 of the world’s best freedivers—test the absolute limits of our amphibious nature.


The first divers show up wearing hooded wetsuits and insectoid goggles, each moving with syrupy-slow steps as they warm up on the sailboat, staring with wide, lucid eyes. One, two, three—they slide into the sea like otters, then lie back looking semicomatose as their coaches slowly float them over to one of three lines dangling from the flotilla.

An official on line one counts down from 10; announces, “Official top”; and begins counting up: “One, two, three, four, five. . .”

The countdowns let the divers know when to start gulping their last breaths of air and prepare to go deep. A female diver on line three, Junko Kitahama of Japan, inhales a few final lungfuls, ducks her head beneath the water, and descends. As her body sinks, the monitoring official announces her depth every few seconds.

Two minutes later, a judge on the surface yells, “Blackout.” Safety divers kick down along the rope and reemerge with Kitahama’s body between them. Her face is pale blue, her mouth agape, her head craned back like a dead bird’s. Through her swim mask, her wide eyes stare into the sun. She isn’t breathing.

“Blow on her face!” yells a man swimming next to her. Another man grabs her head from behind and raises her chin out of the water. “Breathe!” he yells. Someone from the deck of a boat yells for oxygen. “Breathe!” the man repeats. But Kitahama doesn’t breathe. She doesn’t move.

A few agonizing seconds later, she coughs, jerks, twitches her shoulders, and flutters her lips. Her face softens as she comes to. “I was swimming and. . .” She laughs and continues. “Then I just started dreaming!” Two men slowly float her over to an oxygen tank sitting on a raft. While she recovers, another freediver takes her place and prepares to plunge even deeper.

Hanli Prinsloo, a national record holder from South Africa, tells me there’s more to freediving than descending along ropes and trying to beat your opponents. “It offers a stillness,” she told me earlier, a kind of full-body meditation that can be found nowhere else. And there is no need to force yourself down to 300 feet to find it. The most incredible transformation, she said, happens at around 40 feet down. There, the force of gravity seems to reverse; the water stops buoying your body toward the surface and instead starts pulling you deeper.

This is the “doorway to the deep,” where everything changes, and anyone can pass through it—even me. To prove it, Prinsloo offered an introductory out-of-water session where we’d work on increasing my breath-holding capacity, the first step in learning to freedive. My personal breath-hold best was around 50 seconds; she promised that within two hours of training, I’d double it.

Deep Breath

We walk to a covered patio overlooking Messinian Bay and roll out yoga mats. The lesson begins with some basic poses to loosen the muscles around the chest. Through stretching and breathing exercises, freedivers develop up to 75 percent more lung capacity than the average person.

We are now sitting cross-legged facing each other, breathing into the three chambers of our lungs: the belly area, the sternum, and the top of the chest, just beneath the collarbones. Prinsloo says most of us spend our lives breathing only at the very top of our chests. To store more oxygen, I’ll need to learn to breathe into the total volume of my lungs.

Then Prinsloo pulls out her stopwatch and gets ready to time my first attempt. I lie down, take one more enormous three-chambered breath, and hold it. She starts the clock.

What feels like 30 seconds pass. I’m nauseated. My head throbs. I imagine for a moment what it must be like to be 100 feet underwater and feeling this awful. This thought triggers panic. A few seconds later, my body starts convulsing. Prinsloo stops the watch and tells me to exhale, then inhale. I sit up, shaking my head, feeling like a failure.

“Not bad,” she says, showing me the stopwatch. I’ve just held my breath one minute and 45 seconds.

I ask about the convulsions. She explains that the body responds to extreme breath-holding in three stages. Convulsions are the first-stage response. “You start reacting not from the lack of oxygen but from the buildup of carbon dioxide,” she says. “When that starts, it’s just a caution that you’ve only got a few minutes to go before you really need to breathe.” The second-stage response occurs when the spleen releases up to 15 percent more fresh, oxygen-rich blood into the bloodstream. This usually occurs only when the body goes into shock, but it also happens during extreme breath-holding. A freediver anticipates the spleen’s delivery of fresh blood, feels it happen, and uses it as a turbo-charge to dive even deeper.

The third-stage response is blackout, which happens when the brain senses there’s not enough oxygen to support itself and so shuts off, like a switch, to conserve energy. Freedivers learn to sense the arrival of convulsions and spleen release, and they know exactly when to head back to the surface so the third-stage blackout won’t occur.

“There’s a reason we’re built with all these amazing rows of defense,” Prinsloo says, shifting me into yet another yoga pose. “It’s that we are meant to be underwater!”

I lie on my back for my final breath-holding attempt of the day. Inhale, exhale, big inhale, hold. Prinsloo starts the stopwatch. I close my eyes.

After what feels like about 20 seconds, I start gently convulsing again. I tell myself this is natural, to concentrate, keep relaxed, wait for the spleen to kick in. It’s hard to wait. My chest feels pressurized and my heart pounds so forcibly that I can sense it in my hands, legs, crotch. I feel miserable.

“Stick with it. You’re just at the first stage,” Prinsloo reassures me. After what feels like 10 more seconds, my stomach begins constricting, and my throat tenses. I feel claustrophobic. “Just a little longer. . . ,” she says gently. Soon my body feels electrified. I’m wriggling on the mat like a fish out of water. “Right now, your spleen is filling your body with fresh, oxygen-rich blood,” she says. Moments later, I think I can sense what she’s talking about. My body calms. The darkness of my closed eyes grows somehow darker; the ambient noise fades; and I feel like I’m drifting off to. . .

“Breathe!” she says. I exhale, inhale, exhale. I’m dizzy, have trouble focusing through fluttering eyes, but I feel good. “How long do you think that was?” she asks me. I shrug and guess about a minute or so. She smiles. I didn’t just double my breath-holding record—I tripled it. The stopwatch reads three minutes, 10 seconds.

Under Pressure

I could now hold my breath for more than three minutes, but after the dangerous dives and blackouts I’d seen, diving to even a few dozen feet was out of the question. And yet, I was still determined to find out what it was like at a depth of 300 feet.

My best bet in the short term was to talk to William Trubridge. Between 2007 and 2010, Trubridge broke 14 world records (mostly his own) in the disciplines of constant weight without fins and free immersion. Today he is considered the world’s top no-fins and fins-assisted freediver.

“Freediving is [as much] a mental game as a physical one,” says Trubridge. With his cropped hair, wraparound dark glasses, and a worn T-shirt, he’s got the quiet, nerdy energy of a software engineer.

Like almost all competitive divers, Trubridge says he dives with his eyes closed. He’ll open them for a moment when he reaches the plate at the bottom of the rope, but that’s it. By diving blind, he prevents his brain from using up the energy—and oxygen—it would take to process visual information.

So, Trubridge can’t tell me what it looks like 300 feet down, but he can describe how it feels. He leans back and takes a deep breath. And as he starts talking, my stomach starts tightening once again. . .

In the first 30 or so feet underwater, the lungs, full of air, buoy your body, forcing you to paddle as you go down. And you’ve still got 270 feet of swimming to go.

But as you descend past 30 feet, you feel the pressure on your body double and your lungs shrink. You suddenly feel weightless, your body suspended in a gravityless state called neutral buoyancy. Then something amazing happens: as you keep diving, the ocean begins pulling you down. You place your arms at your sides in a skydiver pose, relax, and effortlessly dive deeper.

At 100 feet, the pressure quadruples. The ocean’s surface is barely visible, but you’re not looking anyway. Your skin cools as you prepare for the deep water’s tightening clutch.

Farther still, at 150 feet, you enter a dream state caused by heightened levels of carbon dioxide and nitrogen in your bloodstream. For a moment, you can forget where you are and why.

At 250 feet, the pressure is so extreme that your lungs shrink to the size of fists and your heart beats at less than half its normal rate. Heart rates of freedivers at this depth have been recorded as low as 14 beats per minute; some freedivers have reported heart rates of 7 beats per minute. According to physiologists, a heart rate this low can’t support consciousness. And yet, according to the divers, somehow, deep in the ocean, it does.

At 300 feet, the Master Switch really kicks in. The walls of your organs and vessels, working like pressure-release valves, allow the flow of blood and water into the thoracic cavity. Your chest collapses to about half its original size.

The effects of nitrogen narcosis at 300 feet down are so strong that you forget where you are, what you’re doing, and why you’re in this dark place, fumbling around. Hallucinations are common. You lose motor control. Everything around you appears to slow down.

Then comes the really hard part. Your dive watch beeps, alerting you that you’ve reached your target depth. You open your eyes, force your semiparalyzed hand to grab a ticket from the plate attached to the end of the rope, and then head back up. With the ocean’s weight working against you, you tap your meager energy reserves to swim toward the surface. If you lose concentration now, cough, or even slightly hesitate, you could pass out. But you don’t hesitate or slow down. You hurry and kick back toward the light.

Drawn to Dive

On the final night of the competition, the divers, coaches, and judges gather on the beach for closing ceremonies. Strobes and spotlights glare from an enormous stage, Euro-pop blasts from a DJ booth, and a crowd of a few hundred dance and drink beneath a night sky sequined with stars. Behind the stage a bonfire rages, heating the bare, wet bodies of those who couldn’t resist one last splash.

The winners are announced. All told, the divers broke 2 world and 48 national records. Competitors also suffered 19 blackouts.

“There is such a strong community here,” says Hanli Prinsloo, drinking a cocktail by the bonfire. “It’s like, all of us, we have no choice. We have to be in the water; we’ve chosen to live our lives in it, and by doing that, we accept its risks.” She takes a sip.

“But we also reap its rewards.”

Excerpted from Deep: Freediving, Renegade Science, and What the Ocean Tells Us about Ourselves, by James Nestor. Houghton Mifflin Harcourt, 2014. Reprinted with permission.

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