Ravelo's breathing is slow and deep. His eyes are shut. By calming his mind he will, he hopes, slow his body and quell its thirst for oxygen as he attempts to reclaim his place as the world's deepest breath-holding diver, unaided by breathing equipment -- a title that the Italian Umberto Pelizzari took in 1992. In his category of breath-hold, or "free," diving, called constant-weight, Pelizzari descended 236 feet on a single breath of air. Ravelo aims to descend ten feet farther, looking for a "confirmation tag" attached to a blood-red guide rope that has already been laid deep beneath the platform. If he grabs the tag, the time he took to reach it -- probably about a minute -- will not be the most impressive part of his oxygenless excursion: he set a world record in 1993 by holding his breath for six minutes and forty-one seconds while lying motionless at the bottom of a hotel pool. The true feat is the tremendous exertion required to return to the surface. With his arms extended above him in a hydrodynamic Superman pose, Ravelo must kick against gravity the equivalent of nineteen stories back to air.
Around Ravelo's platform the faces of six scuba divers -- white ovals emerging from dark wet suits -- bob on the Atlantic's steely swells, waiting for Ravelo's move. Stationed at ten-meter intervals, the divers, who will later be joined by breath-hold divers, are ready to serve as links in Ravelo's underwater lifeline. If he passes out, no one of the safety divers can rush him to the surface: they will be anchored to their assigned depths by the perils of the bends, which threaten divers who breathe compressed air and ascend too rapidly. Instead they will pass his unconscious body back to the surface like a baton.
Spectator boats drift away; their engines must not taint the air. Momentarily lapsing from his trance, Ravelo signals to his manager, Rudi Castineyra, among the scuba divers. Castineyra extends his arm into the air and gives a thumbs-down sign -- diver-speak not for "bad" but for "descend." Air hisses out of their buoyancy vests as the divers sink like paratroopers into the clouds. Ravelo's black form remains alone under the gray sky as he prepares his underwater pas seul.
In 1992, in Cuba, Ravelo set the world record for constant-weight free diving at 230 feet -- the record Pelizzari broke only a few months later in Italy, where free divers are celebrated as fervently as bullfighters are in Spain. When Ravelo tried to regain his title in 1993, Cuban security officials refused him a boat, fearing that he would sail for America. Their refusal drove him to flee to Miami.
Ravelo's upper body grows larger and then smaller: his ribs are bowing outward from the pressure of his lungs as he breathes deeply, stretching their capacity for a gigantic last gasp. He makes the puh-puh-puh sounds of a bicycle pump as he swallows air into his digestive system, like a child wanting to burp. This may save Ravelo's life: on the way back up he will belch the gaseous discharge into his lungs. His twenty minutes of breathing techniques complete, a tingling in his fingertips tells him that his body is fully oxygenated. He blows off carbon dioxide with four hard exhales and gasps once. The water accepts him silently.
With a flutter of powerful fin kicks Ravelo propels himself downward. At fifty feet the increasing water pressure compresses the air-filled cavities in his body to a density sufficient for him to sink without effort. He stops kicking, and the force of gravity slices him through the water like an arrow surging toward its target.
RINO Gamba, of the Confédération Mondiale des Activités Subaquatiques (CMAS), has been verifying free-diving records, including Ravelo's, since 1967. "They aren't trying to beat nature," he says of the divers. "They have a deep love of the sea. You cannot understand the strength of their passion."
Gamba points out that human beings have long braved the sea unaided by gadgets. In 1913, thirty years before Jacques Yves Cousteau and Emil Gagnan perfected the self-contained underwater breathing apparatus (SCUBA), a Greek sponge diver, Stotti Geroghios, dove 200 feet without so much as fins and tied a line to the lost anchor of an Italian battleship. Archaeological digs have unearthed widespread evidence of breath-hold diving in seaside cultures. Mother of pearl, for example, harvested from the deep, adorns carved ornaments that date from 3200 B.C. in Thebes and 4500 B.C. in Mesopotamia. Today in Japan female divers known as amas scavenge the ocean floor for pearls and coral at depths of as much as 145 feet for up to three hours a day, returning to the surface as many as ninety times for air. Scuba divers at those depths for this duration would suffer decompression sickness. The ama practice of whistling before a plunge seemed only a custom until scientists discovered that whistling increases air pressure in the lungs, forcing blood out and leaving more volume for the next breath.
Rural peoples of the Mediterranean and the Caribbean buy the daily catch of local spearfishers who hold their breath as they dive. Ravelo himself, before becoming the youngest-ever member of the Cuban national spearfishing team, helped his father support the family by spearfishing. With his spear gun attached by rope to a buoy on the surface, he searched beneath underwater rocks and in caves for groupers, which can be as large as 140 pounds. Once the fish was speared, a buddy at the surface gathered in the line while Ravelo, fresh air in his lungs, returned to untangle the line from rocks or sometimes to fight his catch hand to fin. Today spearfishing has become a sport for thousands around the world. At international championships judges tally points for each fish caught and for their weights; the record for a bluefin tuna caught with a spear gun stands at 398 pounds.
Free diving is not without risk. In the European countries of the Mediterranean alone about fifty-five free divers die each year, many from "shallow-water blackout." With increasing depth, pressure compresses the chest, giving divers the false sensation that their lungs are full. But during ascent pressure drops rapidly and gas in the lungs expands, which can lead to a lack of blood-oxygen and loss of consciousness, often just before divers reach the surface. Pre-dive hyperventilation, as practiced by Ravelo and others, can also put divers at risk by lowering carbon dioxide levels so much that they do not feel the need to breathe soon enough. Mehgan Heaney-Grier, a nineteen-year-old model who established the U.S. women's constant-weight free-diving record at 155 feet, and who accompanied her friend Ravelo to observe his most recent attempt to break a record, explains the danger all free divers face: "You override your brain's message telling you when to breathe. You're running on your reserve tank and there's no warning before you hit empty."
Most free divers neither hunt for fish nor seek to set records. They simply prefer to venture underwater unencumbered by pounds of scuba equipment. "Breath-holders often see things scuba divers don't," says Tec Clark, the assistant director of the YMCA's national scuba program (a U.S. federation of CMAS), based in Norcross, Georgia, which supported Ravelo's attempt as part of its plans to promote free diving more widely. "The aquatic environment accepts you more as a free diver. You get to see fish that might otherwise shy away from bubbles and the noise of scuba mechanisms." Heaney-Grier agrees. She tells stories of riding the backs of twenty-five-foot whale sharks and giant sea turtles on a single breath of air.
THE quest to make the world's deepest dive unaided by breathing equipment began in earnest about thirty years ago, when Enzo Maiorca, an Italian, and Jacques Mayol, a Frenchman born in Shanghai, separately developed methods using heavy weights to speed their descent. As they plummeted five feet per second, they grabbed their noses and blew like crazy, racing against time to equalize the mounting pressure that could otherwise burst an eardrum.
One method, which survives to this day, involves no swimming at all and is known as "no-limits" free diving. Divers hold on to a weighted, rope-guided sled. Delivered by this aquatic luge to the prescribed depth, they detach themselves from the sled and pull a pin that releases compressed air from a cylinder into a balloon, which they grab to buoy themselves back to the surface in a storm of bubbles. In an intermediate kind of free diving, "variable-weight" divers hasten their descent with a sinker of no more than a third of their body weight, which they shed before ascending unaided. In Ravelo's "constant-weight" type of free diving, he completes the round trip without assistance.
In the late sixties Mayol and Maiorca achieved depths approaching 240 feet. Physiologists, groups of whom curiously follow free divers, cautioned them against going deeper. The limit, they said, would be not breath-holding capacity but water pressure, which below 325 feet, they calculated, would collapse the chest like an empty soda can -- an effect known as thoracic squeeze.
But Mayol was convinced otherwise. During his studies of the diving behavior and anatomy of dolphins at the Seaquarium, near Key Biscayne, Florida, he witnessed autopsies that revealed no obvious anatomical structure preventing thoracic squeeze. The lungs and thorax were essentially the same in a dolphin as in a human being, yet dolphins survived great depths. Mayol was sure that whatever protected them would also protect people. Testing himself in waters from the Mediterranean to the frigid lakes of the Andes, and helped by a group of scientists, Mayol sought to understand what happens to the human body underwater. In a typical experiment, Mayol descended to 150 feet and held his breath for nearly four minutes with a cardiac catheter inserted in his chest. When in 1976 he defied warnings and, helped by a sled, went to 328 feet, scientists confirmed the existence of "blood shift" in humans.
We share this mechanism to prevent crushing -- a throwback to our evolutionary aquatic heritage -- with dolphins, seals, and other diving mammals. In response to pressure, the body constricts the blood vessels on the periphery, forcing blood from the extremities into the chest cavity. The thoracic cavity becomes not like an empty soda can but like a full one, blood being incompressible.
Blood shift protected Francisco "Pipin" Ferreras, another native of Cuba who now lives in Florida, when in 1990 he broke Mayol's record for no-limits free diving by going to 367 feet. In 1991 Umberto Pelizzari, Ravelo's nemesis in constant-weight free diving, broke the no-limits record by going to 387 feet.
These records tempt divers to believe that there is no limit to the depths a diver can withstand, but scientists still say otherwise. They worry now not about the crushing of the chest but about cardiac arrhythmias, which they have observed during Ferreras's dives. Claes Lundgren, the director of the Center for Research and Education in Special Environments at the State University of New York at Buffalo medical school, has observed that blood shift causes the heart to swell. Lundgren is also concerned that mounting blood pressure will eventually burst the capillary walls inside the lungs. The potential looms for an unromantic death by cardiac arrest or by drowning in lungs full of blood. "No one seems concerned," he says. "But they will be when somebody finds out what the absolute limit is in a very unpleasant way."
Even without these dangers, the hazards of no-limits diving are drastic. Ferreras, in his most recent world-record attempt, off Cabo San Lucas, at the southern tip of Mexico's Baja Peninsula, successfully descended to and returned from 436 feet. But he had to abort a first attempt, because he drifted into shallow water. Effectively blind without a mask, he raced toward a rocky bottom. Safety divers had to get him off the sled to avoid a crash. Only a few weeks earlier one of Ferreras's safety scuba divers had been found floating dead on the surface. During a training dive he may have had convulsions and therefore returned too quickly to the surface; internal gases, expanding as water pressure decreased, caused the arteries in his organs to explode.
Because of the dangers, dive organizations refuse to sanction no-limits diving. In 1970 CMAS stopped ratifying records, saying that no-limits diving was not a sport but a brand of "applied experimentation," meaning experiments involving people. Many aficionados of free diving are unimpressed with Ferreras and his ilk. Constant-weight has much more finesse, they say. Jacques Mayol's son, Jean-Jacques, who now teaches free diving in Miami, says of no-limits diving, "It's turned into a circus. Anybody who can clear his ears and hold his breath for two minutes can set a no-limits record. It doesn't take a whole lot of skill to hang on to something. But constant-weight I truly admire. They train until every little cell knows how to hold its breath."
WHEN Ravelo stops kicking at fifty feet, he orders his body to sleep for the rest of the ride. Down is the easy part. Everything is on his side. His body is saturated with fresh oxygen and depleted of carbon dioxide -- it is an excess of the latter, not a shortage of the former, that causes the craving to breathe.
Somewhere in the primordial part of his mind the pressure and cold water trigger orders to conserve the oxygen supply in his bloodstream. His spleen shrinks substantially, raising the level of oxygen-enriched hemoglobin. Because blood shift takes blood from the limbs, the burning of oxygen is much reduced -- only the brain and vital organs are drawing it. Receptor cells around Ravelo's lips cue the slowing of his heart by as much as 50 percent -- a phenomenon, known as diving bradycardia, that sometimes allows near-drowning victims to be revitalized forty minutes after sinking into icy water.
Certainly the human body has ways to survive this sort of maneuver -- as free divers argue when they are criticized for going where they do not belong. If we are not meant to descend into deep water, they ask, why are our bodies adapted to it?
Yet Ravelo's maneuver remains risky. The blood shift has reduced oxygen circulating to Ravelo's legs, which must power his return to the surface. Muscular exertion without oxygen is common; the muscles of a champion running a hundred-yard dash operate anaerobically, taking chemical energy from stores within themselves. But Ravelo's anaerobic strength may run out before he hits the surface.
The stopwatch ticks off the hundred and twentieth second; the entire dive is expected to last no more than 135 seconds. Two breath-hold safety divers descend to monitor Ravelo during the last, most dangerous, forty feet to the surface. This is the nether region between conquest and death, where the success shimmering at the surface can yet be snatched away by shallow-water blackout. The two breath-hold divers, unencumbered by equipment or considerations of decompression, can rush Ravelo to the surface if his body goes limp.
They have been below for thirty seconds; the stopwatch has ticked fifteen times since Ravelo was due on the surface -- an eternity in a realm where contingencies are planned to the second. Their finned forms shoot around like huge, nervous baitfish. They know that the current, blown up by recent windstorms, has caught Ravelo off guard. Only later, when the scuba divers return to the surface, will they learn the full extent of the drama. Ravelo achieved his depth but drifted sixty feet from the guide rope. Disoriented, struggling against the current, he grabbed at a video-camera light instead of the reflector to which his confirmation tag was fixed. "When he realized his mistake," his manager said afterward, "he tried to go deeper, thinking he had farther to go." Another twenty seconds was lost while he wrestled with the cameraman. "I thought he would take my spare air supply and breathe," his manager continued, "but he went for the tag and started his ascent."
By the time the divers spot Ravelo, his legs are powerless. Sinking, he desperately claws for the surface with his arms. Then he goes limp.
Two minutes and forty-three seconds. The safety divers burst to the surface with Ravelo's motionless form between them. "Breathe!" they shout. "Breathe!" With all their might they slap their friend's face. His limp floating body is as blue and dark as the ocean. The speedboat roars over and a medic has an oxygen mask over Ravelo's face before his fins are out of the water. No one cares that the record attempt has failed.
Bobbing in another swell, Mehgan Heaney-Grier looks at something in her hands. It is the confirmation tag, which she found floating on the surface.
A FEW days after he returns from the hospital, Ravelo sits comfortably in a friend's living room, planning the next attempt. He is not intimidated by the blackout he suffered: he "pinked up" right after the mask was put on his face; the blood he vomited was only seepage from burst capillaries in his sinuses. He's had that before. "What we've learned," he says through his manager, who interprets, "is that we have to be where the seas are calm. We may go to the Caribbean or the Mediterranean. A record of this nature can be attempted only in perfect conditions."
Nor is Ravelo discouraged. He claims that Mayol has aborted many of his dives in panic, and so has Ferreras. He must go forward. Now, he feels, he has an advantage: he reached the depth.
But has he not learned something about tempting fate? Is he not worried that he has gone too far?
Ravelo shrugs. "Even the fish were uncomfortable in the sea that day," he says. Then, more thoughtfully, in his rapid-fire Spanish, he tells of the most painful time of his life. It was in 1994, when he was interred for a year at Guantanamo, the U.S. military base on the island of Cuba, where refugees were processed before they could come to America. "Every day I could see the sea but I could not go to it." He craved the sensations of a deep dive. The ocean has become, after all, his second home.