I lost consciousness during a deep freedive, but a strange vision saved me from drowning
Return to Galicia, land of my childhood
The day I cheated death dawned bright and sunny. I awoke in my father’s beach house in Galicia, Spain. I had come from the United States with my American girlfriend to vacation with my family. It was July 1988, and I was 31, in the prime of life and still brimming with that sense of immortality enjoyed by the young.
Galicia is a Celtic country in the northwest corner of Spain. Surrounded by the cold waters of the Atlantic, it is misty, rainy and green. It features tall mountains, deep valleys and a jagged coast of bays, islands, white sand coves and granite cliffs. That is the place where I grew up. It always entices me back with the feeling of morriña – a deep and abiding longing for this magical land.
The southwest coast of Galicia is marked by a series of bays called the Rías Baixas. Protected by mountains from the prevailing north winds, their water warms enough in the summer for swimming, sailing and diving. The beach of Menduiña, where my family’s summer house is located, is a jewel on the eastern shore of the Bay of Aldán, the smaller of those bays. I spent the summers of my childhood there, learning to swim and, soon after, to freedive.
Freediving
Freediving is diving while holding your breath. It is different from scuba diving - in which you breathe from a tank of compressed air - and from snorkeling - in which you swim at the surface breathing from a snorkel. Competition freediving consist in diving as deep as possible. The world record, held by Herbert Nitsch, is at 214 meters (702 feet). Most people freedive to spearfish, catch shellfish or sightsee. These dives are shallower, and the objective is to maximize bottom time. In Spain, spearfishing is only legal while freediving.
Freediving became my passion in my early teens. The water was cold, but that barely slowed me down. After seeing me repeatedly exit the water shivering near hypothermia, my father bought me one of the first wetsuits sold in Spain. Soon afterwards, he gave me a compressed-air speargun. By age 15, I was diving to 12-15 meters (40-50 feet), and even deeper, just for fun. I often brought home enough fish to feed my parents and seven siblings.
Gone spearfishing
In 1988, I had been abroad several years working as a neuroscientist, first in Paris and later at the National Institutes of Health in Bethesda, Maryland. This holiday was an opportunity to revisit the aquatic pleasures of my youth.
A neighbor, Fernando, offered his company and his Zodiac inflatable boat for a spearfishing adventure.
I still had my dive gear and was eager to relive the good old times. We motored to one of my favorite diving spots: a rocky reef surrounded by deep water that had plenty of fish. Soon I had bagged several large sargos (Diplodus Sargus), a delicious species and my favorite catch.
However, Fernando was having trouble. The tide was a bit high and he couldn’t dive as deep as I could. So we decided to leave the reef and go to the nearby bateas, where we could spearfish from the surface.
Bateas are unique to the bays of Galicia, where they are used to cultivate mussels and oysters. They are stationary rafts consisting of floats that support a grid of logs. Thick ropes hang down and descend deep into the water. Mussels are attached to the ropes, and when they grow large enough they are harvested by pulling up the ropes. The mussel-encrusted ropes form columns up to two feet thick. In the shadows between, sea life flourishes. These artificial reefs are simple and eco-friendly ocean farms.
The temptation
We tied the Zodiac to a batea about half a mile from the shore. I jumped in the water without my speargun, since I had caught all the fish I wanted. But it wasn’t long before my partner came looking for me.
“I dropped my speargun when I jumped in the water,” he said. “Can you dive to the bottom and get it?”
“You’re crazy!” I said. “Do you have any idea how deep it’s here? It must be at least 20 meters! I can’t possibly dive that deep.”
“Never mind, then. I brought another speargun.”
He grabbed his other speargun and swam around the batea, looking for a place where we hadn’t spooked the fish.
I went sightseeing, diving down the fantastical columns formed by the mussel-encrusted ropes. It is scary to dive when you cannot see the bottom, just a blackness that my imagination turns into a frightening abyss. However, when I dove to the end of the ropes, the clouds of plankton opened up and the water became very clear. I saw rocks at the bottom and, sure enough, there was Fernando’s speargun, daring me to come down and grab it.
I swam back to the surface.
It was otherworldly and beautiful in the depths. I asked myself, was I being honest when I said that I couldn’t dive that deep? The truth was, I didn’t know. I had probably done it before but, not having a depth gage, it was impossible to know for sure.
On the other hand, I haven’t been diving for a while.
But I was in top shape. The water felt like home.
I decided to go for it.
The dive
I prepared meticulously. Floating effortlessly at the surface, I closed my eyes and relaxed. Then I started my hyperventilation routine. After a couple of minutes, I took some last deep breaths and filled my lungs to their maximum capacity. My chest felt uncomfortably over-inflated, but I knew that this sensation would disappear as I descended.
I pinched my nose through my mask. Bending sharply at the waist, I went upside down with my legs high in the air. As soon as my fins hit the water, I swam as fast as I could, going straight for the bottom. I repeatedly blew through my nose in the Valsalva maneuver to keep the pressure from hurting my ears.
A freedive demands full, unhesitating commitment. I had to race to the bottom as fast as possible to minimize my use of oxygen. I kicked my fins with a steady rhythm, conserving energy. The diving reflex kicked in, and I felt my heart slowing down. I was suffused with a sense of peacefulness and power.
Fifteen meters down, my lungs were empty, compressed by the surrounding pressure of the water. Further down, they fully collapsed and I felt my throat sinking into my chest. It’s a weird feeling, but I was used to it after many years of freediving.
Like my lungs, the air cells in my thick neoprene wetsuit compressed with the pressure. A wetsuit makes you float so much that it’s impossible to dive. To compensate, you wear a belt with enough weights to make you are just a bit positively buoyant at the surface. However, as pressure compresses the air cells in the neoprene, you turn negatively buoyant. That means that, past a certain depth, you sink. The only way back to the surface is to swim up.
With the combined speed of sinking and swimming, I nearly crashed against the rocks at the bottom. They were bare of the gorgeous seaweed common in Galicia. I was so deep that there was not enough sunlight for seaweed to grow.
I saw the speargun and grabbed it.
That’s when things started to go wrong. Competition freedivers know that the moment you turn around to go back to the surface is decisive. If you don’t get it just right, you can waste too much energy and oxygen. That’s what happened to me. I wasn’t used to hit the bottom and go back up. I normally swam at the bottom and then head for the surface.
As ascended, the air hunger kicked in, stronger than I expected. I should have released my weight belt or, even better, unbuckled it and held it in my hand, so if I passed out I would drop it to the bottom. But I didn’t feel the need to do that. I just swam to the surface as fast as I could. That gave me enough momentum to reach a depth at which I became positively buoyant. Even though I lost consciousness on my way up, I floated to the surface.
The lamas
I found myself on a vast plain. Two Buddhist monks stood next to me, their saffron robes shining in the sun. One of them was talking, and I listened in amazement at his wisdom. They were looking at each other, not paying attention to me. I interrupted him to ask a question.
“I am glad that you like my teachings,” said the lama, turning to look at me. “But you have more pressing problems right now.”
“What problems?”
“You are drowning.”
“Not, I am not. How can I drown here, on dry land?”
“Can’t you feel the taste of salt water in your mouth?”
I tried to taste my mouth and, sure enough, it was full of salt water.
Something yanked me away from the plain.
I was at the surface, being gently rocked by the waves.
The lama was right. I was about to die.
I ripped my snorkel out of my mouth, stuck my head out of the water, and took a deep breath of air.
The recovery
Floating in the water, I felt like was about to pass out again. I put the snorkel back into my mouth and blew it clear of water. That way, I could breathe even if I was unconscious. The corner of the batea was just above my head, so I pulled myself onto it and balanced precariously on the logs until Fernando returned.
We motored back to the beach and hauled our gear and my catch to the house. I briefly told my American girlfriend what happened, and that I felt sick and was going to bed.
“What can I do?” she said, shocked, terrified and relieved at the same time.
“Eat the fish,” I replied.
Shallow water blackout and hyperventilation
What happened to me is called shallow water blackout or hypoxic blackout. Counter-intuitively, it is more common among experienced freedivers than among beginners. The diver loses consciousness underwater from oxygen deprivation. Unable to regain the surface, or to breathe at the surface, he drowns.
Paradoxically, deep diving helps you hold your breath longer. As pressure increases, more oxygen crosses the walls of the alveoli of the lungs into the blood. However, when the diver ascends there is a drop of pressure in the lungs that accelerates oxygen depletion. This is why loss of consciousness happens during the ascent, hence the moniker “shallow water blackout.”
Being a scientist, I did some research on the physiology of freediving and hypoxic blackout. I was not willing to give up my underwater passion, especially since we had moved to California, which is as rich with sea life as Galicia. I just had to find a way to do it safely.
Doctors blame shallow water blackout on hyperventilation, and recommend against it.
They argue that it cannot increase blood oxygen because red blood cells are saturated with oxygen when they leave the lungs. What hyperventilation does is to decrease blood CO2, which is what triggers ‘air hunger’- the need to breathe. Oxygen gets depleted while CO2 is still low, making the diver feel that he can still hold his breath. Below a certain oxygen level, the brain shuts down and the diver loses consciousness. The more experienced the free diver, the more she is able to hold her breath to the limit. This explains why experienced free divers are more susceptible to hypoxic blackout.
Does hyperventilation increase oxygen storage?
Most freedivers still practice hyperventilation because experience tells them that it substantially increases bottom time. Not any hyperventilation will do; there are special techniques that are better at saturating the body with oxygen. I use kapalabhati, a yoga breathing method that I have been practicing since college.
There is a scientific explanation why hyperventilation works. First of all, it is not true that normal breathing completely saturates the blood with oxygen, especially if you have a high red blood cell count, as do many athletes. Measured with a pulse-oximeter, my blood oxygen at rest is not 100%, but 94%. This may not seem much of a difference, but it is when you consider that the hemoglobin in red blood cells supplies other oxygen stores in the body. The main one is the myoglobin of the muscles, a protein that has the same heme molecule as hemoglobin. It is used to store oxygen for muscle consumption. The brain has a heme-containing protein called neuroglobin, so it also can store a small amount of oxygen.
The importance of myoglobin in storing oxygen while diving is underscored by its presence in marine mammals. Seals, whales and dolphins have lots of myoglobin in their muscles, which they use to store oxygen while they dive. Striped dolphins and false killer whales have 10 times as much myoglobin (66 mg/g) as dogs (7 mg/g) or rats (2 mg/g). Humpbacked, dusky and bottlenose dolphins have somewhat less myoglobin (23 mg/g). Humans have 15-40 mg myoglobin per gram of dry muscle; however, these numbers would be much lower if expressed per gram of fresh muscle, which are the amounts given above for cetaceans.
Myoglobin does not release oxygen back into the blood. Muscles consume the oxygen it stores instead of oxygen in the blood, leaving more oxygen available for other tissues.
Using oxygen stores in their blood and muscles, elephant seals and some whales can dive for up to two hours, while dolphins remain underwater for 8-10 minutes. Trained freedivers can dive to 70 meters for 2 minutes or more. The world record of static apnea (holding your breath without diving or swimming) is a stunning 24 minutes and 33 seconds. It was achieved after hyperventilating in pure oxygen, which proves that it is possible to store a great deal of oxygen in the human body.
If not hyperventilation, what caused my blackout?
I attribute my blackout to a combination of causes:
Not having been freediving for several years.
Doing repeated deep dives without enough recovery in between.
Diving too deep for my current abilities.
Being tired after a long session of diving.
Based on marine charts and scuba diving later on in that area, I estimate that my dive was to 18-20 meters (60-66 feet). Years later, I repeatedly dove to 75 feet off Casino Point on Catalina Island. That time I had a depth gauge, and several scuba divers watching for safety. I used hyperventilation and reached the surface comfortably.
Near-death experiences
The most intriguing question is not why I passed out, but why I recovered consciousness.
Many divers drown at the surface when they are unconscious, unable to blow their snorkel clear of water to breathe. If the brain shuts down for lack of oxygen, one would expect that it would not recover unless its oxygen supply is restored. So, why did I wake up to save my life?
There are many reports of ‘near-death experiences’ - the visions and feelings of peace that some people experience when going into terminal shock or approaching death. Similarly, I was overcome with peace and a sense of being near a source of wisdom. I practiced Zen Buddhism at the time, which may explain why, instead of seeing God or a gate to Heaven, I saw wise Buddhist monks. Maybe, in extreme conditions, the mind goes through an altered state of consciousness that is interpreted through the lens of the beliefs of the individual. I do not believe in the supernatural or life after death, and this experience did not change my mind. I think what matters is not the visions, but the emotions and the altered state of consciousness that accompanies them.
Near-death experiences may be triggered by the anomalous state of the dying brain. Sleep is an active state in which one part of the brain, the reticular formation, turns off other parts of the brain. Terminal unconsciousness is different: parts of the brain may be activated or inactivated at random, depending on their need for oxygen. Near-death experiences may produce a decoupling of brain regions similar to that produced by psychotropic drugs.
Or maybe this process is not random at all. Since drowning and accidental unconsciousness were common in our evolutionary environment, perhaps we evolved a mechanism to jump-start the brain as a last resort for survival. For example, there could be a release of noradrenaline or corticotropin-releasing factor and in the amygdala to trigger a fight-or-flight response and thus wakefulness. This noradrenaline release was read by my mind as the monk telling me that I was drowning… Get out of your peaceful, near-death Nirvana, and fight for your life!