Skip to main content
x

The Edge: The World's Most Epic Dives and Their Scuba Pioneers

By Paul Kvinta | Updated On January 30, 2017
Share This Article :

The Edge: The World's Most Epic Dives and Their Scuba Pioneers


Diving on the Edge

Shutterstock

Playing with fire: The spectacular collision of molten lava and seawater can produce unpredictable explosions of rock and scalding steam.

As a sport, scuba diving doesn't bother with the trivial accumulation of points or the impressing of judges. Ours is an inherently barrier-smashing pursuit of pure exploration, one that transports the practitioner beyond the sport itself and thrusts him into whole new universes. Scientists dive to study the feeding habits of great whites. Archaeologists dive to uncover lost civilizations. With little more than technology and our own imaginations holding us back, what are the limits?

Where is the edge?

The places featured in this article constitute the extreme boundaries of diving. They are the hottest, the coldest, the highest, the longest and the deepest. These are not, however, merely stories of place, but also of the pioneers who boldly charted those places. Whether it was Johan Reinhard dragging his tanks up one of the world's tallest volcanoes, or Sam Meacham pressing into the forbidden netherworld of the planet's deepest cave system, these folks pushed scuba to the next level. Of course, most divers will never get anywhere near Licancabur or Ox Bel Ha, and that's understandable. But that doesn't mean you'll never dive at altitude or explore a cave someday. Read these tales for inspiration.

Every day since 1983, the Kilauea volcano has spewed 2,000-degree lava into the Pacific.

The Hottest: Kilauea

"I've seen fish swimming around with burns on them," claims lava diver Bill DeRoy. "Really, you see them." Well, you see them when you dive where 2,000-degree molten lava rushes into the ocean, as DeRoy occasionally does in the shadow of the world's most active volcano, Kilauea, off the southeast coast of Hawaii's Big Island. This angry, 4,000-foot mountain has been spewing magma every day since 1983, and when the glowing liquid oozes down Kilauea's Eastern Rift Zone to the shoreline and makes contact with those huge Pacific swells, divers who dare to plunge here witness all hell breaking loose. Literally.

When lava mixes with seawater, spectacular events unfold, all of them extremely hot, all of them extremely dangerous. At the surface, lava instantly transforms water into steam, causing dramatic explosions and launching rocks, molten fragments and scalding water 40 feet into the air. Beneath the surface, lava-filled boulders can explode, sometimes shooting flames through the water, while others implode, causing concussive, body-throttling booms! Boiling pools of water rise and settle at the surface, and, with all this activity, great visibility often disappears without warning. "Lava is moving at you from every direction," says DeRoy, who has worked as a safety diver with videographers shooting this mayhem. "Boulders the size of La-Z-Boys are falling down all around you. Anyone shooting footage needs a safety diver almost attached to him, ready to move him in a split second."

In 1971, underwater cameraman Lee Tepley and volcanologist James Moore made the first-ever lava dive to investigate one of the many flows produced by Kilauea since the 1950s. Tepley's award-winning footage featured "pillow lava," long tubes of brilliant red magma that snake through the water before hardening, turning black and then bursting open again to birth new tubes. Since then, about 100 scientists, documentarians and adrenaline junkies have dived with lava off Kilauea, the only place in the world where this particular brand of fate tempting takes place. So far, no one has died doing this, but there have been close calls, especially involving underwater landslides. When enough volcanic rubble collects along the steep submerged slope where lava enters the ocean, the shaky pile can instantly give way, as it did in 1987 with DeRoy's team filming at 50 feet. "There was an increase in implosions and these firecracker sounds, and we all looked up at the same time and saw it coming," he recalls. "Our visibility disappeared in seconds." Suddenly in the dark, the team clutched together as debris tossed, twirled and dragged them down the slope. When everything finally settled down, they found themselves at 150 feet. A few days later, another landslide hauled Tepley down to 300 feet. He swore off lava diving forever.

Given current instability at the site, DeRoy and most others haven't dived there in about a year, but conditions could change overnight; such is the unpredictability of Kilauea. "No one tells Madame Pele what to do," DeRoy warns, referring to the revered Hawaiian volcano goddess. "She is very, very powerful."


Photography by Paul Aguilar

The polar ice sheet floats on the Arctic Ocean, with massive slabs of ice rumbling and colliding.

Diving under ice and in the shadows of glaciers has become hugely popular among divers. But not many have been to the North Pole.

The Coldest: The North Pole


Photography by Paul Aguilar

With 28-degree water and sub-zero surface temps, your dive hole can close up quickly

There's nothing jolly or elfish about Santa's backyard. Ask Bob Wass. When he led the first successful dive expedition at the geographic North Pole in 1999, two of his team's cold-water regulators froze up, a weight belt cracked and popped off one diver, and another's fins crumbled upon exiting the 28-degree water for a topside temperature of 40 below zero. And these were just niggling concerns compared with the big picture. "You're on floating ice on the ocean," says Wass, a native Long Islander. "The ice can crack beneath you without warning. Your dive hole can close or freeze over pretty quickly. Anything can happen."

Think of the North Pole as a giant, rumbling motel ice machine. Unlike Antarctica, a solid landmass, the 1,200-mile-wide ice sheet that blankets the top of the earth is forever shattering and reforming, with drifting slabs of frozen tonnage constantly slamming into one another, grinding, cracking, uplifting and shaping whole new landscapes. Sometimes the pole sits exposed in the open Arctic Ocean. Other times, it's covered by 40 feet of ice. The only thing certain about diving this forbidden icescape is when to do it, and that's April, when the ferocious winds and storms that rage here for 11 months abate somewhat, offering a brief window for intrepid souls to don insulated underwear and dry suits and slip beneath the ice.

The first attempt to dive the pole in 1998 ended in disaster when Andrei Rozhkov, leader of a Russian team, inexplicably went limp and died minutes into a solo dive. His teammates had to sit with his body for three days after an ice storm prevented helicopters from rescuing them. Team members later said they'd seen mysterious spotlights and heard a deafening "sonar ping" right before Rozhkov's death, prompting speculation that a patrolling Russian submarine may have caused his demise. One year later, fortunately, Wass's nine-man international team experienced no such Clancyesque episode. The men choppered in from a Russian-operated "ice airport" 60 miles from the pole and set up a toasty staging tent next to an open "lead" between two ice plates. They filled their tanks on-site, as the humidity in pre-filled tanks would have frozen instantly. Then they plunked into the water and found a world both eerie and dazzling. Beyond a few translucent shrimp and jellyfish, the place was virtually lifeless and still, with the seafloor some two-and-a-half shadowy miles beneath them. But when they gazed up at the surface they saw what appeared to be a ceiling full of chandeliers. Says Wass: "There were these beams of turquoise light, refracting through all that broken ice. It was spectacular."

Since then, a handful of tourists and scientists have dived the pole, including Paul Aguilar, who each April burns a hole through the ice to retrieve a mooring lined with dozens of sensing devices for the National Science Foundation's North Pole Environmental Observatory program. "Sure, it's cold," says Aguilar. "But it's possible to over-prepare. Last time, if you can believe this, I was way too warm. Next year, I'm wearing less fleece under my dry suit."

The Highest: Licancabur


Photography by Johan Reinhard

The lake on top of Licancabur.

Strictly speaking, as a body of water, the crater lake atop Licancabur volcano in Chile possesses all the scuba excitement of a YMCA lap pool. The lake's surface area isn't much bigger than that, its depth reaches a meager 20 feet, and unless you're a fan of zooplankton, there are no gape-worthy critters finning about in there. Still, it's hard to ignore the one damn-impressive feature about this place — Licancabur's water-filled crater sits high above the clouds at 19,200 feet, making it the loftiest dive site on record.

It earned that status in the early 1980s when Johan Reinhard, an explorer in residence for the National Geographic Society and a real-life Indiana Jones, scaled the volcano in his ongoing search for high-altitude Inca sacred sites. The mountain-climbing, scuba-diving archaeologist — noted particularly for his 1995 discovery at 20,000-plus feet of an Inca mummy dubbed the "Inca Ice Maiden" — had read about ruins along the rim of Licancabur, and he'd heard murmurings about something even more enticing. "There was this legend about a gold statue in the lake," he says, explaining that the Incas often made offerings into Andean lakes to appease various gods.

In April 1980, Reinhard summited the snow-covered mountain and saw the frozen lake for the first time. He returned during the summer in 1981 and made several free dives in the 40-degree water, although the oxygen-deprived mountain air made reaching the shallowish bottom a Herculean task, even for Reinhard, who free-dives to 50 feet in the ocean. Nevertheless, the lung-burning plunges revealed brilliant clouds of red, yellow and brown zooplankton, a discovery that, along with the possibility of cultural artifacts, prompted Reinhard and four others to plot a return a year later with scuba gear and cameras.

Beginning at 4,900 feet, the team made three grueling trips up Licancabur's steep, rocky slopes, schlepping dry suits, regulators, lead weights and a rubber dinghy. They also hauled tanks of pure oxygen, as Reinhard figured they could enjoy the benefits the gas provided at altitude without running the risk of toxicity, given the shallow depth of the lake. Dive tables at the time provided bottom times only for dives up to 14,000 feet of altitude, so the team extrapolated the numbers to 19,200. Over four days, they made 11 dives, methodically scouring the lake bottom with a metal detector. Alas, unlike his many gold and silver discoveries in other high Andean lakes, Reinhard found no submerged artifacts. Still, like any discovery-bound scientist, he did find satisfaction in one important, if obscure, find--a new species of zooplankton, carefully collected, sealed in formaldehyde and shuttled down the mountain.

Reinhard insists he climbs and dives only in pursuit of science, and while he reckons he'll dive Licancabur again to continue his research, he doesn't see himself diving above that. "I don't know of a higher body of water," he says, "let alone one with Inca ruins near it."

The Longest: Ox Bel Ha


Photography by Sam Meacham

After 350 dives in the system, explorer Bil Phillips is still obsessed with Ox Bel Ha. To date, divers have mapped just 45 percent of the passages.

On a map, the flooded tunnels of Ox Bel Ha (ohsh-bel-ha) bear a frightening resemblance to Medusa's frenzied do — passages snaking wildly in all directions, looping, twisting and crisscrossing. For 66 miles they weave a tangled knot beneath the jungles and beaches of Mexico's Yucatan Peninsula, transporting fresh water from the interior to the sea and forming the world's longest underwater cave system. And divers have seen only half of it. "We've explored a fraction, maybe 45 percent," says Sam Meacham, co-founder of the eight-person team that literally put Ox Bel Ha on the map. "If that's the case, it's the second-longest cave in the world, wet or dry, after Mammoth Cave."

Despite its monster size, Ox Bel Ha has not consumed any of the explorers who've dared to map it, a remarkable feat given cave diving's reputation as the world's most dangerous sport (431 deaths since the 1960s, a significant number considering the relatively few practitioners). In cave diving, panic leads to death, and it's easy to panic in dark, water-filled crevices deep beneath the earth's surface. "It requires an almost hypnotic state to keep you focused," says co-founder Bil Phillips, whose team has made 350 dives in the system over six years. "You must move slowly. The introduction of adrenaline would be a killer. Fortunately, we've got an experienced group."

When Phillips and Meacham first strapped on tanks and dropped into a cenote, or sinkhole, deep in the jungle in 1998, they were hopeful. The Yucatan's porous limestone is pocked with more than 3,000 cenotes, many leading to subterranean complexes, and by 1998 other teams had already explored two vast systems nearby, Nohoch Nah Chich and Dos Ojos. At the bottom of Cenote Esmeralda, Phillips and Meacham discovered something tantalizing--a giant, fossil-littered thoroughfare they later named "The Mayan Skyway," 100 feet wide and 30 feet tall, with side passages branching off everywhere. Subsequently, over the course of several expeditions, the team pushed deeper and laid survey line, with individuals sometimes using six tanks to make seven-hour, two-and-a-half-mile dives. They later incorporated rebreathers and underwater scooters. For the most part, the experience has been scare-free, although there have been moments. "One day we were standing around a cenote, and we heard screams for help," recalls Fred Devos. "One of our divers was cruising across the cenote behind a scooter with a crocodile on her heels. I picked up a log, but I'm thinking, 'What am I going to do with a log?' " Fortunately, the croc finally lost interest.

These days the edgiest thing about Ox Bel Ha isn't its size or the crocodiles--it's the rapid rate of development spreading down the peninsula from Cancun. Sprawling resorts here inject sewage deep into the ground, a potentially devastating practice for the Yucatan's pristine water and caves. Meacham and Phillips are scrambling to educate folks about the resources just below their feet. "We started doing this for the thrill of exploration," says Meacham. "But now there's a different challenge, and it's hard, trying to preserve something people can't see."

The Deepest: Edmund Fitzgerald

The inspiration for Gordon Lightfoot's haunting ballad lies in dark, frigid water 530 feet below the surface of Lake Superior. That's deep, no doubt about it. But what makes this site particularly edgy, in addition to its depth, are the buzz-saw emotions still connected to the Fitz, as Terrance Tysall and Mike Zee discovered when they made the first and only scuba dive there in 1995. "Logistically and physiologically, it was a challenge, and we just wanted to prove it could be done," recalls Tysall. "I had no idea people would respond the way they did."

On Nov. 10, 1975, the SS Edmund Fitzgerald, a 729-foot ore carrier, capsized in a monster storm in Canadian waters 17 miles northwest of Michigan's Whitefish Point. All 29 crewmen perished. Remote cameras later dispatched by the Coast Guard found the ship in two pieces on the lake bottom, the bow upright, the stern upside down. Since then, a handful of expeditions using ROVs and submersibles has visited the site, including Jacques Cousteau in 1980. In 1994, one expedition returned with photographs of dead crewmen and the intentions to publish them. Incredulous, surviving families had a judge block the scheme, and the Michigan legislature responded by outlawing photography of corpses on Great Lakes bottomlands.

So the pot had been well-stirred before Tysall, an explorer with the Cambrian Foundation, and Zee stepped off the R/V First One in 1995 and dropped quickly through blackness toward the Fitz. Descending face-to-face to monitor each other for high-pressure nervous syndrome, the pair breathed air for three minutes before switching to trimix at 250 feet. At 490 feet, they spied the wreck and then dropped another 40, landing on the port-side rail just behind the pilothouse. The dive wasn't without emotion. As Tysall would later write, "We gently gripped the ghostly rail with both hands. For the first time in almost 20 years, living hands were touching the Edmund Fitzgerald." After only 12 minutes at the site, they began a three-hour ascent with the help of two safety divers who shuttled them tanks of nitrox. Except for some minor glitches, the dive was a success.

To some Fitz families, however, it was an outrage. With their loved ones well-preserved in 33-degree water, the last thing families wanted were packs of divers nosing around, a sentiment that caught Tysall off-guard. "I think people were worried we were trying to be gruesome or something," he says, "but that wasn't the case at all." He promised the families he would keep his video footage — which he insists depicts no bodies — under wraps, even with the tabloid program Hard Copy clamoring for it. Still, the episode added urgency to efforts already under way by families to lobby Canada for a dive ban. In 2001, the parliament authorized the creation of strict regulations designed to protect all of Canada's "heritage wrecks." The details are still being hammered out, but diving the Fitz could very well be made a punishable offense. Richard Ingalls, a Detroit attorney who assists the surviving families, hopes that whatever regulations Canada produces will have teeth, in the form of heavy fines or jail time. Says Ingalls: "It's a grave site. Men are entombed in that ship. It deserves respect."

How Deep Is Deepest?

Admittedly, we're being a bit subjective here with our superlatives. How, for example, does one determine the deepest dive? For the purposes of this particular envelope-pusher, we're talking open-water dives on open-water gear. Yes, a handful of folks have traveled deeper than 530 feet, the depth of the Edmund Fitzgerald. But those record-focused ocean plunges have amounted to little more than digits on a dive computer. They've lacked a sense of place and could have been done anywhere. The one wreck dive arguably deeper than the Fitz, a 2000 expedition to the German battleship Baden off England's Channel Islands in 548 feet of water, deteriorated into a morass of invective among team members as to what if anything was accomplished. No one, on the other hand, questions the Fitz dive — not the guys who did it, nor the people they upset doing so.

The Coldest: The North Pole > You probably won't be headed to the North Pole itself — no commercial operators go there — but some companies can ferry you well above the Arctic Circle, where you'll explore underwater icebergs and swim with belugas and narwhals. For maximum comfort under the ice, you'll need not only a dry suit but appropriate duds beneath: a well-fitting undersuit made of high-tech microfibers, wool socks and a cashmere scarf. Before you go, take an ice-diving specialty course, and you'll learn why you should purchase a cold-water regulator or adapt yours with a cold-water kit.

The Highest: Licancabur > While you likely won't be gunning for any 19,000-foot crater lakes, there are plenty of high lakes in the U.S. worth exploring, like Lake Tahoe at 6,227 feet, with its huge schools of fingerling trout and rugged granite formations. Remember that an increase in altitude often means a decrease in water temperature, so plan accordingly. PADI offers special training in altitude diving.

The Hottest: Kilauea > Content yourself with witnessing the sculpted results of Hawaii's many ancient and recent lava flows — the dramatic arches, tubes, caves, canyons, pinnacles and domes that lie off each island. Of particular note: Sheraton Caverns off Kauai, Makaha Caves and Shark's Cove off Oahu, Cathedrals off Lanai, and Kaiwi Point, Golden Arches and Chimney off the Big Island.

The Deepest: Edmund Fitzgerald > Legally and emotionally, you'd do well to avoid the Fitz altogether and concentrate on, say, the equally famous Andrea Doria, the 700-foot liner that went down off Nantucket in 1956. She rests in 240 feet of water, and Mad Dog Expeditions, www.maddogexpeditions.com, leads trips for experienced dry suit and trimix divers. Of course, diving beyond 120 feet presents serious decompression issues, so you'll need plenty of tech training before dropping in on any deep wrecks. Both NAUI and TDI/SDI teach extended range and mixed gas courses, and every agency offers a wreck specialty.

The Longest: Ox Bel Ha > Ox Bel Ha remains off-limits to all but the current explorers, but you can plunk into another Yucatan system, Dos Ojos, the world's third-largest, and experience 300-foot visibility, giant rooms and ceilings studded with limestone daggers. Cave diving also demands loads of intensive training.

Diving on the Edge

Shutterstock

Playing with fire: The spectacular collision of molten lava and seawater can produce unpredictable explosions of rock and scalding steam.

As a sport, scuba diving doesn't bother with the trivial accumulation of points or the impressing of judges. Ours is an inherently barrier-smashing pursuit of pure exploration, one that transports the practitioner beyond the sport itself and thrusts him into whole new universes. Scientists dive to study the feeding habits of great whites. Archaeologists dive to uncover lost civilizations. With little more than technology and our own imaginations holding us back, what are the limits?

Where is the edge?

The places featured in this article constitute the extreme boundaries of diving. They are the hottest, the coldest, the highest, the longest and the deepest. These are not, however, merely stories of place, but also of the pioneers who boldly charted those places. Whether it was Johan Reinhard dragging his tanks up one of the world's tallest volcanoes, or Sam Meacham pressing into the forbidden netherworld of the planet's deepest cave system, these folks pushed scuba to the next level. Of course, most divers will never get anywhere near Licancabur or Ox Bel Ha, and that's understandable. But that doesn't mean you'll never dive at altitude or explore a cave someday. Read these tales for inspiration.

Every day since 1983, the Kilauea volcano has spewed 2,000-degree lava into the Pacific.

The Hottest: Kilauea

"I've seen fish swimming around with burns on them," claims lava diver Bill DeRoy. "Really, you see them." Well, you see them when you dive where 2,000-degree molten lava rushes into the ocean, as DeRoy occasionally does in the shadow of the world's most active volcano, Kilauea, off the southeast coast of Hawaii's Big Island. This angry, 4,000-foot mountain has been spewing magma every day since 1983, and when the glowing liquid oozes down Kilauea's Eastern Rift Zone to the shoreline and makes contact with those huge Pacific swells, divers who dare to plunge here witness all hell breaking loose. Literally.

When lava mixes with seawater, spectacular events unfold, all of them extremely hot, all of them extremely dangerous. At the surface, lava instantly transforms water into steam, causing dramatic explosions and launching rocks, molten fragments and scalding water 40 feet into the air. Beneath the surface, lava-filled boulders can explode, sometimes shooting flames through the water, while others implode, causing concussive, body-throttling booms! Boiling pools of water rise and settle at the surface, and, with all this activity, great visibility often disappears without warning. "Lava is moving at you from every direction," says DeRoy, who has worked as a safety diver with videographers shooting this mayhem. "Boulders the size of La-Z-Boys are falling down all around you. Anyone shooting footage needs a safety diver almost attached to him, ready to move him in a split second."

In 1971, underwater cameraman Lee Tepley and volcanologist James Moore made the first-ever lava dive to investigate one of the many flows produced by Kilauea since the 1950s. Tepley's award-winning footage featured "pillow lava," long tubes of brilliant red magma that snake through the water before hardening, turning black and then bursting open again to birth new tubes. Since then, about 100 scientists, documentarians and adrenaline junkies have dived with lava off Kilauea, the only place in the world where this particular brand of fate tempting takes place. So far, no one has died doing this, but there have been close calls, especially involving underwater landslides. When enough volcanic rubble collects along the steep submerged slope where lava enters the ocean, the shaky pile can instantly give way, as it did in 1987 with DeRoy's team filming at 50 feet. "There was an increase in implosions and these firecracker sounds, and we all looked up at the same time and saw it coming," he recalls. "Our visibility disappeared in seconds." Suddenly in the dark, the team clutched together as debris tossed, twirled and dragged them down the slope. When everything finally settled down, they found themselves at 150 feet. A few days later, another landslide hauled Tepley down to 300 feet. He swore off lava diving forever.

Given current instability at the site, DeRoy and most others haven't dived there in about a year, but conditions could change overnight; such is the unpredictability of Kilauea. "No one tells Madame Pele what to do," DeRoy warns, referring to the revered Hawaiian volcano goddess. "She is very, very powerful."

Photography by Paul Aguilar

The polar ice sheet floats on the Arctic Ocean, with massive slabs of ice rumbling and colliding.

Diving under ice and in the shadows of glaciers has become hugely popular among divers. But not many have been to the North Pole.

The Coldest: The North Pole

Photography by Paul Aguilar

With 28-degree water and sub-zero surface temps, your dive hole can close up quickly

There's nothing jolly or elfish about Santa's backyard. Ask Bob Wass. When he led the first successful dive expedition at the geographic North Pole in 1999, two of his team's cold-water regulators froze up, a weight belt cracked and popped off one diver, and another's fins crumbled upon exiting the 28-degree water for a topside temperature of 40 below zero. And these were just niggling concerns compared with the big picture. "You're on floating ice on the ocean," says Wass, a native Long Islander. "The ice can crack beneath you without warning. Your dive hole can close or freeze over pretty quickly. Anything can happen."

Think of the North Pole as a giant, rumbling motel ice machine. Unlike Antarctica, a solid landmass, the 1,200-mile-wide ice sheet that blankets the top of the earth is forever shattering and reforming, with drifting slabs of frozen tonnage constantly slamming into one another, grinding, cracking, uplifting and shaping whole new landscapes. Sometimes the pole sits exposed in the open Arctic Ocean. Other times, it's covered by 40 feet of ice. The only thing certain about diving this forbidden icescape is when to do it, and that's April, when the ferocious winds and storms that rage here for 11 months abate somewhat, offering a brief window for intrepid souls to don insulated underwear and dry suits and slip beneath the ice.

The first attempt to dive the pole in 1998 ended in disaster when Andrei Rozhkov, leader of a Russian team, inexplicably went limp and died minutes into a solo dive. His teammates had to sit with his body for three days after an ice storm prevented helicopters from rescuing them. Team members later said they'd seen mysterious spotlights and heard a deafening "sonar ping" right before Rozhkov's death, prompting speculation that a patrolling Russian submarine may have caused his demise. One year later, fortunately, Wass's nine-man international team experienced no such Clancyesque episode. The men choppered in from a Russian-operated "ice airport" 60 miles from the pole and set up a toasty staging tent next to an open "lead" between two ice plates. They filled their tanks on-site, as the humidity in pre-filled tanks would have frozen instantly. Then they plunked into the water and found a world both eerie and dazzling. Beyond a few translucent shrimp and jellyfish, the place was virtually lifeless and still, with the seafloor some two-and-a-half shadowy miles beneath them. But when they gazed up at the surface they saw what appeared to be a ceiling full of chandeliers. Says Wass: "There were these beams of turquoise light, refracting through all that broken ice. It was spectacular."

Since then, a handful of tourists and scientists have dived the pole, including Paul Aguilar, who each April burns a hole through the ice to retrieve a mooring lined with dozens of sensing devices for the National Science Foundation's North Pole Environmental Observatory program. "Sure, it's cold," says Aguilar. "But it's possible to over-prepare. Last time, if you can believe this, I was way too warm. Next year, I'm wearing less fleece under my dry suit."

The Highest: Licancabur

Photography by Johan Reinhard

The lake on top of Licancabur.

Strictly speaking, as a body of water, the crater lake atop Licancabur volcano in Chile possesses all the scuba excitement of a YMCA lap pool. The lake's surface area isn't much bigger than that, its depth reaches a meager 20 feet, and unless you're a fan of zooplankton, there are no gape-worthy critters finning about in there. Still, it's hard to ignore the one damn-impressive feature about this place — Licancabur's water-filled crater sits high above the clouds at 19,200 feet, making it the loftiest dive site on record.

It earned that status in the early 1980s when Johan Reinhard, an explorer in residence for the National Geographic Society and a real-life Indiana Jones, scaled the volcano in his ongoing search for high-altitude Inca sacred sites. The mountain-climbing, scuba-diving archaeologist — noted particularly for his 1995 discovery at 20,000-plus feet of an Inca mummy dubbed the "Inca Ice Maiden" — had read about ruins along the rim of Licancabur, and he'd heard murmurings about something even more enticing. "There was this legend about a gold statue in the lake," he says, explaining that the Incas often made offerings into Andean lakes to appease various gods.

In April 1980, Reinhard summited the snow-covered mountain and saw the frozen lake for the first time. He returned during the summer in 1981 and made several free dives in the 40-degree water, although the oxygen-deprived mountain air made reaching the shallowish bottom a Herculean task, even for Reinhard, who free-dives to 50 feet in the ocean. Nevertheless, the lung-burning plunges revealed brilliant clouds of red, yellow and brown zooplankton, a discovery that, along with the possibility of cultural artifacts, prompted Reinhard and four others to plot a return a year later with scuba gear and cameras.

Beginning at 4,900 feet, the team made three grueling trips up Licancabur's steep, rocky slopes, schlepping dry suits, regulators, lead weights and a rubber dinghy. They also hauled tanks of pure oxygen, as Reinhard figured they could enjoy the benefits the gas provided at altitude without running the risk of toxicity, given the shallow depth of the lake. Dive tables at the time provided bottom times only for dives up to 14,000 feet of altitude, so the team extrapolated the numbers to 19,200. Over four days, they made 11 dives, methodically scouring the lake bottom with a metal detector. Alas, unlike his many gold and silver discoveries in other high Andean lakes, Reinhard found no submerged artifacts. Still, like any discovery-bound scientist, he did find satisfaction in one important, if obscure, find--a new species of zooplankton, carefully collected, sealed in formaldehyde and shuttled down the mountain.

Reinhard insists he climbs and dives only in pursuit of science, and while he reckons he'll dive Licancabur again to continue his research, he doesn't see himself diving above that. "I don't know of a higher body of water," he says, "let alone one with Inca ruins near it."

The Longest: Ox Bel Ha

Photography by Sam Meacham

After 350 dives in the system, explorer Bil Phillips is still obsessed with Ox Bel Ha. To date, divers have mapped just 45 percent of the passages.

On a map, the flooded tunnels of Ox Bel Ha (ohsh-bel-ha) bear a frightening resemblance to Medusa's frenzied do — passages snaking wildly in all directions, looping, twisting and crisscrossing. For 66 miles they weave a tangled knot beneath the jungles and beaches of Mexico's Yucatan Peninsula, transporting fresh water from the interior to the sea and forming the world's longest underwater cave system. And divers have seen only half of it. "We've explored a fraction, maybe 45 percent," says Sam Meacham, co-founder of the eight-person team that literally put Ox Bel Ha on the map. "If that's the case, it's the second-longest cave in the world, wet or dry, after Mammoth Cave."

Despite its monster size, Ox Bel Ha has not consumed any of the explorers who've dared to map it, a remarkable feat given cave diving's reputation as the world's most dangerous sport (431 deaths since the 1960s, a significant number considering the relatively few practitioners). In cave diving, panic leads to death, and it's easy to panic in dark, water-filled crevices deep beneath the earth's surface. "It requires an almost hypnotic state to keep you focused," says co-founder Bil Phillips, whose team has made 350 dives in the system over six years. "You must move slowly. The introduction of adrenaline would be a killer. Fortunately, we've got an experienced group."

When Phillips and Meacham first strapped on tanks and dropped into a cenote, or sinkhole, deep in the jungle in 1998, they were hopeful. The Yucatan's porous limestone is pocked with more than 3,000 cenotes, many leading to subterranean complexes, and by 1998 other teams had already explored two vast systems nearby, Nohoch Nah Chich and Dos Ojos. At the bottom of Cenote Esmeralda, Phillips and Meacham discovered something tantalizing--a giant, fossil-littered thoroughfare they later named "The Mayan Skyway," 100 feet wide and 30 feet tall, with side passages branching off everywhere. Subsequently, over the course of several expeditions, the team pushed deeper and laid survey line, with individuals sometimes using six tanks to make seven-hour, two-and-a-half-mile dives. They later incorporated rebreathers and underwater scooters. For the most part, the experience has been scare-free, although there have been moments. "One day we were standing around a cenote, and we heard screams for help," recalls Fred Devos. "One of our divers was cruising across the cenote behind a scooter with a crocodile on her heels. I picked up a log, but I'm thinking, 'What am I going to do with a log?' " Fortunately, the croc finally lost interest.

These days the edgiest thing about Ox Bel Ha isn't its size or the crocodiles--it's the rapid rate of development spreading down the peninsula from Cancun. Sprawling resorts here inject sewage deep into the ground, a potentially devastating practice for the Yucatan's pristine water and caves. Meacham and Phillips are scrambling to educate folks about the resources just below their feet. "We started doing this for the thrill of exploration," says Meacham. "But now there's a different challenge, and it's hard, trying to preserve something people can't see."

The Deepest: Edmund Fitzgerald

The inspiration for Gordon Lightfoot's haunting ballad lies in dark, frigid water 530 feet below the surface of Lake Superior. That's deep, no doubt about it. But what makes this site particularly edgy, in addition to its depth, are the buzz-saw emotions still connected to the Fitz, as Terrance Tysall and Mike Zee discovered when they made the first and only scuba dive there in 1995. "Logistically and physiologically, it was a challenge, and we just wanted to prove it could be done," recalls Tysall. "I had no idea people would respond the way they did."

On Nov. 10, 1975, the SS Edmund Fitzgerald, a 729-foot ore carrier, capsized in a monster storm in Canadian waters 17 miles northwest of Michigan's Whitefish Point. All 29 crewmen perished. Remote cameras later dispatched by the Coast Guard found the ship in two pieces on the lake bottom, the bow upright, the stern upside down. Since then, a handful of expeditions using ROVs and submersibles has visited the site, including Jacques Cousteau in 1980. In 1994, one expedition returned with photographs of dead crewmen and the intentions to publish them. Incredulous, surviving families had a judge block the scheme, and the Michigan legislature responded by outlawing photography of corpses on Great Lakes bottomlands.

So the pot had been well-stirred before Tysall, an explorer with the Cambrian Foundation, and Zee stepped off the R/V First One in 1995 and dropped quickly through blackness toward the Fitz. Descending face-to-face to monitor each other for high-pressure nervous syndrome, the pair breathed air for three minutes before switching to trimix at 250 feet. At 490 feet, they spied the wreck and then dropped another 40, landing on the port-side rail just behind the pilothouse. The dive wasn't without emotion. As Tysall would later write, "We gently gripped the ghostly rail with both hands. For the first time in almost 20 years, living hands were touching the Edmund Fitzgerald." After only 12 minutes at the site, they began a three-hour ascent with the help of two safety divers who shuttled them tanks of nitrox. Except for some minor glitches, the dive was a success.

To some Fitz families, however, it was an outrage. With their loved ones well-preserved in 33-degree water, the last thing families wanted were packs of divers nosing around, a sentiment that caught Tysall off-guard. "I think people were worried we were trying to be gruesome or something," he says, "but that wasn't the case at all." He promised the families he would keep his video footage — which he insists depicts no bodies — under wraps, even with the tabloid program Hard Copy clamoring for it. Still, the episode added urgency to efforts already under way by families to lobby Canada for a dive ban. In 2001, the parliament authorized the creation of strict regulations designed to protect all of Canada's "heritage wrecks." The details are still being hammered out, but diving the Fitz could very well be made a punishable offense. Richard Ingalls, a Detroit attorney who assists the surviving families, hopes that whatever regulations Canada produces will have teeth, in the form of heavy fines or jail time. Says Ingalls: "It's a grave site. Men are entombed in that ship. It deserves respect."

How Deep Is Deepest?

Admittedly, we're being a bit subjective here with our superlatives. How, for example, does one determine the deepest dive? For the purposes of this particular envelope-pusher, we're talking open-water dives on open-water gear. Yes, a handful of folks have traveled deeper than 530 feet, the depth of the Edmund Fitzgerald. But those record-focused ocean plunges have amounted to little more than digits on a dive computer. They've lacked a sense of place and could have been done anywhere. The one wreck dive arguably deeper than the Fitz, a 2000 expedition to the German battleship Baden off England's Channel Islands in 548 feet of water, deteriorated into a morass of invective among team members as to what if anything was accomplished. No one, on the other hand, questions the Fitz dive — not the guys who did it, nor the people they upset doing so.

The Coldest: The North Pole > You probably won't be headed to the North Pole itself — no commercial operators go there — but some companies can ferry you well above the Arctic Circle, where you'll explore underwater icebergs and swim with belugas and narwhals. For maximum comfort under the ice, you'll need not only a dry suit but appropriate duds beneath: a well-fitting undersuit made of high-tech microfibers, wool socks and a cashmere scarf. Before you go, take an ice-diving specialty course, and you'll learn why you should purchase a cold-water regulator or adapt yours with a cold-water kit.

The Highest: Licancabur > While you likely won't be gunning for any 19,000-foot crater lakes, there are plenty of high lakes in the U.S. worth exploring, like Lake Tahoe at 6,227 feet, with its huge schools of fingerling trout and rugged granite formations. Remember that an increase in altitude often means a decrease in water temperature, so plan accordingly. PADI offers special training in altitude diving.

The Hottest: Kilauea > Content yourself with witnessing the sculpted results of Hawaii's many ancient and recent lava flows — the dramatic arches, tubes, caves, canyons, pinnacles and domes that lie off each island. Of particular note: Sheraton Caverns off Kauai, Makaha Caves and Shark's Cove off Oahu, Cathedrals off Lanai, and Kaiwi Point, Golden Arches and Chimney off the Big Island.

The Deepest: Edmund Fitzgerald > Legally and emotionally, you'd do well to avoid the Fitz altogether and concentrate on, say, the equally famous Andrea Doria, the 700-foot liner that went down off Nantucket in 1956. She rests in 240 feet of water, and Mad Dog Expeditions, www.maddogexpeditions.com, leads trips for experienced dry suit and trimix divers. Of course, diving beyond 120 feet presents serious decompression issues, so you'll need plenty of tech training before dropping in on any deep wrecks. Both NAUI and TDI/SDI teach extended range and mixed gas courses, and every agency offers a wreck specialty.

The Longest: Ox Bel Ha > Ox Bel Ha remains off-limits to all but the current explorers, but you can plunk into another Yucatan system, Dos Ojos, the world's third-largest, and experience 300-foot visibility, giant rooms and ceilings studded with limestone daggers. Cave diving also demands loads of intensive training.