Surviving the Extremes: A Doctor's Journey to the Limits of Human Endurance (25 page)

Pablo didn’t die and Mauro didn’t die—and Mauro didn’t lie. His body corroborates his story. The condition in which Mauro Prosperi was found, and in which Pablo Valencia was found in a different era and in a different desert, is not explainable any other way. Prosperi’s body provides compelling testimony to the kind of damage the desert can inflict and, at the same time, evidence of what the body can sustain when pushed to its extremes. He competed against the desert as a decided underdog, but he won, turning in the performance of his life.

MY AIR BUBBLES WERE ACTING STRANGELY
. As I exhaled into my regulator they sank through the water, floated below my feet, and bumped against the tunnel’s slanted floor. I watched as they rolled on downward and out of sight—then realized that I was upside down.

There was no other way to tell at the moment. I was inside a flooded lava tube, a channel that once vented molten rock from an underwater volcano into the sea. The entrance was a nearly round hole 6 feet in diameter in a smooth mound of rock 30 feet below the water’s surface. The tube was lined with a thick layer of fine sediment and ran as straight and smooth as a drinking straw, angling steadily downward to who knows where.

I had come upon the vent unexpectedly and entered it without a dive buddy or any standard caving equipment, such as a reel of rope to be paid out along the route from the entrance so that I could always find my way back. But the tunnel had no side branches, and I could still see the light at the entrance. Swimming diagonally downward, I had penetrated about 50 feet in, to a depth of 90 feet. The light was growing dim and I was about to turn around when I saw a sea lion coming rapidly up out of the depths. Sea lions are large, gentle creatures that often amuse me on dives in the Galapagos Islands, but this one was heading straight toward me in a narrow tunnel and collision, or at least a playful bump, seemed imminent. I held my mask with one hand and my regulator with the other, afraid to have either one
or both knocked away by the impact. The sea lion loomed close enough for me to count the whiskers on his face, then deftly changed course, wiggling past me with no contact whatsoever. My maneuvers hadn’t been nearly as graceful. My dive to the floor of the tunnel had stirred up a layer of sediment that formed into a thick cloud of fine black powder. It spread widely and then hung suspended in the water, obscuring my view of the tunnel and diffusing the light enough so that I could no longer tell from which direction the light was coming. It would take hours, maybe even days, for the tiny silt particles to settle. The air in my tank would last me at least another forty minutes so long as I didn’t get nervous and start breathing rapidly. There was plenty of time for me to get out of the tunnel—if I knew which way to go. I couldn’t tell up from down, in from out. My weight was exactly counterbalanced by the buoyancy of the water, so I felt no downward pull from gravity. There was nothing to hear except my breathing, and nothing to see except the barely discernible rock walls of a tunnel that no longer had a top and bottom.

I rotated myself until the line of exhaled air bubbles bisected my forehead, meaning that I was upright, and then followed the line, since it was pointing to the ceiling. The trapped air was pooling in a crevice of the rocky wall. Some seemed to be escaping off to one side, however, which meant that side of the wall was higher, and since the tunnel was more or less uniformly slanted, I started swimming that way, kicking up more silt as I went because I couldn’t see where I was going. I expected to come through the cloud at any moment but it extended much farther than I thought. Maybe the silt was sinking down through the tunnel and I was swimming down along with it. Just as I was beginning to think I should turn around, my ears popped. Air in a diver’s ear maintains itself at the same pressure as the surrounding water. Near the surface, the ear senses less pressure and responds by snapping open its relief valve. The pop meant that I was going up. I swam ahead a few more strokes and emerged from the cloud of silt. A beacon of light, the cave entrance, led to the open sea.

What had been a leisurely dive turned into a minisurvival test because of a close encounter with a playful sea lion. He was in his
natural element. I was in a hostile environment, sustained by an elaborate set of artifices that gave me such a false sense of security that I had entered without a buddy or a rope. My air tank, regulator, buoyancy-compensation vest, wet suit, weight belt, mask, and fins made me comfortable under water, but they didn’t make me into a marine mammal. Closer to the limits of my survival than I had realized, I was nearly overcome by a problem that would have been trivial for any true sea creature.

Being under the water and inside the earth at the same time brings on a sense of total isolation from the outside world—a mixture of anxiety and tranquillity that draws people into underwater caves, explained my friend and fellow diver Henri Cosquer, as he began to tell me an incredible story. For years Henri has owned and operated a diving school in Cassis, a picturesque fishing village on the southern coast of France. Surrounded by white limestone cliffs that plunge precipitously into the Mediterranean Sea, creating a series of narrow fiords called
callanques,
Cassis became a resort after being overrun by the French Riviera.

Though I had spent much time exploring the
callanques
—climbing to the tops and diving to the bottoms—I never gave much thought to what might lie inside them. Neither had most other people; fewer still had the skills to find out. In the course of one of his thousands of dives, Henri came across a 6-by-3-foot hole in the rock at a depth of 122 feet. He passed it dozens of times on other dives before curiosity got the better of him and he spontaneously decided to go in. The opening was coral-encrusted, but after about 15 feet the coral faded away as the light dimmed. Henri swam on for another 60 feet, until the light from the cave entrance was a pinpoint behind him, and then turned around. It wasn’t safe to go any farther—this time. But the cave was intriguing. He’d be back.

With lanterns and backup lights, Henri returned to make a series of dives. Each time he penetrated farther. He noted that the tunnel was rising steadily. At a bifurcation, he followed one branch to a dead end, 150 feet from the entrance. The next dive he followed the other branch, and eventually came to a narrow, body-sized constriction in the rock walls. Shining his light through it, he could see that it opened
up on the other side. He was 500 feet inside the tunnel but only 40 feet below sea level.

Henri returned with more equipment. He was able to pass through the tight space only by taking his tank off and passing it in ahead of him, while keeping his regulator tightly clamped in his mouth. On the other side, the tunnel continued straight on another 30 feet, then the walls suddenly sloped up and out to form a vast underwater chamber. The roof was a mirror, reflecting the beam of Henri’s searchlight back down at him. He knew that meant surface water and that there was air above. He swam upward, broke the surface, and found himself inside a huge cave. Shining his light around him he saw that he was in a pool 100 feet wide surrounded by a rocky shore with fluted spires of limestone—stalagmites from below and stalactites hanging from the roof. He felt as if he had entered a temple of the sea. Not quite believing that any of this could be real, he swam to the shore, took a few steps on the rocks, and touched the stalagmites. He said they were warm, like they were still alive. Then he dove into the pool and swam back to the rest of the world.

On the next dive to his secret cave, Henri tried to explore a little more, but both his searchlight and backup light malfunctioned and he barely made his way back through the pitch-dark cave and tunnel. The episode scared him so badly that he didn’t return to the cave for three years. Perhaps he really had violated the sanctity of a sacred temple. Finally, he returned with other divers, laid in a safety rope, and explored the cave further. There were no other entrances. The cave was deep inside the
callanque
yet above sea level, the oxygen presumably coming through twisted crevices that allowed in air but not light. In the total blackness, Henri advanced with his lantern. He stopped for a short rest and placed the light alongside him. It illuminated a small section of the wall with a strange shape on it. Henri brought the lamp closer. It was a painting of a human hand.

Henri’s first reaction was that it was impossible. How could someone else have gotten to this spot with paint and brush and then carefully drawn a hand on the wall? Henri and the other divers began a systematic search, beaming up their lights to scan the walls in every corner of the cave. What they found left them stunned. There were
dozens of paintings—of penguins, caribou, birds, buffalo, and horses—all carefully designed in a very simple, very primitive style. Henri had indeed not been the first person to enter this place. Far from it. He was standing in a temple where humans had come to worship twenty-seven thousand years ago.

But how could they have gotten there? A layer of rock that hadn’t budged in a million years sealed the roof and walls. The only access was through the floor, but to enter that way meant diving 122 feet below the surface and then swimming 537 feet in total darkness. Henri had needed full scuba gear, and even then it took him several attempts. Henri is short, stocky, and full-bearded, and proud to say that he looks like a caveman—his dive boat is named
Cro-Magnon
—but he admits that even his ancient relatives would have been unable to make the dive on a single breath.

Nevertheless, breath-hold diving, also called free diving, has a tradition going back into prehistory; there is evidence that Neanderthals practiced it forty thousand years ago. For at least six thousand years it has been done professionally by women in Japan and the South Pacific, who dive holding large stones to help them sink quickly to depths as great as 100 feet. The diver then spends a minute or so collecting seaweed, shellfish, pearls, and anything else of commercial value before she is pulled back to the surface by a rope tied around her waist. Ancient Greek frogmen practiced breath-holding so that they could stay underwater long enough to cut the anchor lines of enemy ships. Only in the past few hundred years has man developed the technology to stay underwater longer than one breath.

The earliest efforts were diving bells—inverted wooden jars that were lowered beneath the surface with air trapped inside. Since the air was quickly exhausted, more advanced models were made with hoses connected to air pumps at the surface. A comparable system was developed thousands of years earlier by water spiders, which weave airtight silk umbrellas attached to underwater plants. They fill these umbrellas with air by trapping it between their legs at the surface and carrying it down in the form of bubbles. Underneath their air-filled domes, they lie in wait for prey.

To increase mobility for a human diver, the diving bell was reduced
to the size of a helmet, and with that the era of hard-hat diving began. For any one diver, however, the era would end abruptly if he lost his balance, since his tilted helmet would immediately fill with water. Adding a cumbersome watertight suit to seal out the water made movement tortuously slow, but at least the enclosed diver could bend over without drowning. The big advance in diving came only about sixty years ago, when a demand regulator—a gas valve that responds to pressure changes—was combined with a tank of compressed air to create a self-contained underwater breathing apparatus, or scuba. Scuba diving provided the reliability and freedom of movement that at last allowed humans to travel through the most alien and least explored of all the extreme environments on earth.

The realm beneath the waves is a cold, dark, airless world, seemingly without gravity. Humans fend off these dangers with a rubber wet suit, waterproof lights, compressed air, and a buoyancy-compensation vest, but as we descend farther and farther into the sea we become increasingly vulnerable to the sheer weight of the water above us. Water is more than a thousand times heavier than air. As a diver descends, he must support the weight of the water, steadily increasing by the ton. The enormous pressure pushes in on the body, compressing it evenly on all sides. The only reason the diver is not crushed is that, like the sea, his body is made mostly of water—a liquid nearly impossible to compress. But bodies have four hollow spaces that are filled with air—a gas that compresses very easily. Inhaled air is channeled in four directions. Most of it is drawn through the trachea into the lungs. Some passes to the back of the throat, where it is swallowed and works its way down the digestive tract. A small amount of air flows into the skull, via small ducts that lead to the sinuses or through larger tubes that carry it into the middle ear. If the air pressure in each space is not continually pumped up to match the increasing water pressure as the diver descends, his body cavities will very quickly collapse.

The lungs would be the first to feel the squeeze. At a depth of 1 foot there would already be nearly 200 pounds of pressure on the chest wall. One more foot down would be the limit for inhaling atmospheric air; below that level the pulmonary muscles are not strong enough to expand against water pressure. A fleeing prisoner who hides
underwater and breathes with a hollow reed in his mouth had better be in muddy water because he can only submerge 2 feet if he expects to keep breathing.