1:18 PM 9/10/1998
NO ROOM FOR MISTAKES
In the world of scuba diving, exploring underwater caves represents the ultimate challenge - and the most dangerous
Tom Iliffe disappears into the warm green waters of a sacred Mayan pool on Mexico's Yucatán Peninsula
and descends 100 feet to the entrance of an unexplored cave.
Carrying two tanks of compressed air, 50-watt lights to illuminate the darkness and reels of braided line to
lay as a guide for the journey back, the scuba-suited Iliffe glides into the cave, a long, underwater tunnel whose
course and destination are unknown. Its only previous explorers stopped after less than 200 feet.
Iliffe passes blind cave fish and shrimp, the end of the line laid by the previous explorers and scalloped walls
with occasional dried-mud patterns preserved in the rock. He collects plankton and other small creatures in a special
At about 1,000 feet into the cave, Iliffe turns back. He has passed neither the adjoining corridors nor the
stalactites and stalagmites so common among cave systems. He can detect no end in sight.
"Incredible," Iliffe, a professor at Texas A&M University at Galveston, says upon surfacing. "It
appears to be one long tube carrying water to the coast."
Iliffe is a cave-diving scientist, the father of the field and one of still only a handful of his kind in the
world. For the last 20 years, he has traveled around the world studying caves -- caves of absolute darkness, where
rivers flow underground and wrong turns can be fatal, where millions of years of evolution have created, for those
trained to see it, some of the world's most gorgeous scenery. Underwater caves are one of exploration's few remaining
frontiers, and Iliffe is the expedition leader.
From Mexico to Fiji to Yugoslavia, Iliffe has made more than 1,000 dives, in all manner of caves: freshwater
and saltwater; inland and ocean; shallow and deep; plain and ornate; labyrinthine and simple; easily reached and
arduously accessed; entirely underwater and alternately air-filled and underwater.
He's helped map at least 100 caves where no one has gone before and explored another 50 or so farther than previous
divers. He's discovered two new orders, four new
families, 32 new genera and more than 100 new species of animals,
some close relatives of each other, even though they're separated by caves halfway around the world and haven't
been found anywhere in between.
It is work sometimes called "the most dangerous science. "At any moment a cave diver risks loose ceilings;
silt that rises from the floor of disturbed passages to darken water that was transparent going in; vertigo, induced
by huge irregular chambers that confuse some people to the point they can't tell up from down; mind-numbing cold
and depth; and a list of tasks to perform that would overload the mental faculties of most people.
Indeed, so dangerous is cave diving that most cave divers with more than five years' experience have participated
in the recovery of at least one diver's body; the cave diver once considered the best in the business, Sheck Exley,
made 36 recoveries -- before dying in a bid to dive to a record depth. Jacques Cousteau almost died his one time
in a cave.
"That's why we don't promote cave diving, why the first thing we tell people interested in it is the risks,"
says Bruce Ryan, head of the National Speleological Society's cave-diving section. "If you don't realize all
that can go wrong, cave diving isn't for you, because so much can go wrong."
Of course, to some divers, caves are underwater Everests, the supreme test, the chance to do what no one has
done before. What is less forgiving, after all, than a journey into a subterranean, underwater environment where
the only known fact about it is the point where it begins? At least, unclimbed mountains can be studied for possible
ascent routes through aerial or satellite photos.
The most audacious of such cave divers, considered the equivalent of 1950s-era jet test pilots, have penetrated
cave systems to a distance of nearly 10,000 feet and a depth of nearly 1,000 feet -- a depth at which the pressure
can make a diver's mix of air toxic and shut down his or her central nervous system, causing immediate death.
But to Iliffe, who rarely dives deeper than 200 feet, caves are natural laboratories. They provide clues to
how life survives without light, how species of a common ancestor evolve differently in different environments,
how the boundary between fresh water and salt water affects biological processes.
Thanks to what divers have found in them -- skeletal remains of prehistoric sea creatures and artifacts from
ancient civilizations -- caves also open windows into the past. Remains of mammoths and mastodons, and shark and
manatee ancestors have been found in them, the latter two buried when areas now honeycombed with caves were part
of the ocean, the former when they were part of the land; artifacts recovered were left by people who believed
sacrifices to the gods of rain or the inner earth would bring good fortune.
Yet as much as the caves provide a wealth of scientific information, it is their visual appeal that most seduces
Iliffe. With their spectacular stalactite and stalagmite formations, shafts of sunlight penetrating openings, crystalline
waters, and swallows and bats darting about, they can outshine Carlsbad Caverns.
"I think the thing I like best about caves is the sense of age you get entering them, like a great castle,"
says Iliffe. "But whereas castles and other man-made things you can visit are hundreds of years old, these
caves are tens of thousands of years old."
Actually, on his trip this summer to Mérida, the Yucatán capital, Iliffe explored caves whose
origins date to the meteorite that killed the dinosaurs 65 million years ago. The giant meteorite hit close to
the northern Yucatán coast, scientists believe, stirring up so much dust it blocked out sunlight all over
the Earth and created a 100-mile-wide crater that, over the next 65 million years, filled with sediment and rock.
Caves formed as rain seeped through soft, porous limestone and eroded tunnels, which filled with water as the
sea level rose and fell. In some places, the erosion caused cave roofs to collapse, leaving mysterious pools --
some the size of a lake and some immeasurably deep. These are cenotes, Mayan for "sacred reservoirs."
About 1,000 years ago, the Mayans built their civilization around the cenotes. On a peninsula without
surface lakes and rivers, cenotes were the main sources of drinking water and, as portals to another world,
sites of sacrifices --pottery, gold and jewelry, even humans, usually virgins. At the cenote that gave way
to the tubular cave -- Xlacah, the center of Dzibilchaltún, the longest-occupied city of the Maya -- some
600 artifacts have been recovered, most now housed in a nearby museum.
The cenotes dot the Yucatán peninsula. There are thought to be thousands of them, most undiscovered.
The ones that have been discovered form a ring where the meteorite hit, and Iliffe suspects that at one time, at
least, the cenotes probably were connected to each other and their waters flowed into the ocean. But only
a small percentage of the discovered cenotes have been explored, and it is these, hidden amid the land's
thatched Mayan huts, Roman Catholic churches and jungle, that Iliffe and his team of student divers journeyed here
this summer to dive.
The sites include cenotes where entering is as easy as jumping in. Others are so narrow and far down
that divers must descend a long ladder while their scuba equipment is lowered on a rope from another opening. Getting
to some cenotes requires arduous trips through the jungle; Iliffe tells of hiking for hours, scuba equipment
in tow, to probe native people's memories of possible cenotes, often to no avail.
`Something's not right," says Brett Dodson, one of Iliffe's students. "I'm winded. My arm hurts."
Dodson has just exited the Dzibilchaltún cenote after a two-hour, 20-minute dive that took him
173 feet down in search of cave fauna and water samples where fresh and salt water come together.
More than half the dive was spent ascending. Since deep dives cram nitrogen into the blood like carbonated water,
divers make decompression stops on the way up, to shed the nitrogen gradually. Rising without stopping would tear
joints and muscles from within.
But the danger isn't over upon surfacing. Even if a diver follows a computer-prescribed ascent rate, as Dodson
did, nitrogen can sometimes remain in the blood or joints and cause pain or difficulty breathing. The condition,
known as the bends or decompression sickness, can cause paralysis or even death if not treated.
Iliffe and the other divers don't waste any time confirming Dodson's bends. They remove his scuba gear, help
him inside their rental car and take off for a hospital.
No one knows if Dodson will have to be flown by helicopter to Cancún, or if there's a nearby hospital
with a decompression chamber, the pressurized tank that compresses the bubbles back into fluids, then slowly lowers
the pressure so the nitrogen leaves the body without excessive bubbling.
Dodson is lucky. Although northern Yucatán is no dive resort -- Mérida doesn't have any dive shops,
for instance --one of its hospitals six months ago acquired a decompression chamber. Dodson spends the night in
it and is cleared to leave the hospital in the morning, but he'll do no more diving the rest of the trip.
"There's risk in everything, "says Iliffe on the way to the hospital to pick up Dodson the next morning.
"If you dive enough, you risk getting the bends. Still, I worry more about getting in an accident driving
to the airport for these trips than I do about cave-diving accidents. As long as you are properly trained and equipped,
follow the basic rules and stick to reasonable depths, cave diving is not that dangerous."
In the early days of cave diving, most deaths occurred among open-water divers who lacked training and panicked
in new circumstances. More recently, deaths have come among envelope-pushing explorers traveling farther and farther
into the most daunting cave systems.
Iliffe, 50, has been diving since he was a student at Penn State University in the late 1960s. He started cave
diving as a hobby in the late '70s when he took a job in Bermuda doing oil-pollution research. It was virgin territory,
and Iliffe, smitten with the mystery of caves, jumped at the chance to do marine research no one had done before.
Today, cave diving is almost trendy, although not many scientists have followed Iliffe into the field. There
are now more than 14,000 certified cave divers in the United States, up from just 1,000 in 1984, and national organizations
report another 1,000 are being added to the ranks every year.
Twenty years after those initial days in Bermuda, Iliffe has lost none of his enthusiasm for cave diving. Married
and the father of a 5-year-old son, balding, white-bearded and crow's-footed, he is as indefatigable as his students
in searching for a cave, as quick with the sneaky wit and impish grin when the opportunity is ripe.
Those years in Bermuda, 1977 to 1989, made Iliffe's reputation. It was there that his many discoveries debunked
the idea, popular in biology books of the time, that past their entrances, underwater caves contained no life forms.
It was there that he discovered Typhlatya iliffei, a small, blind cave shrimp, the first of numerous cave
animals named for him.
"If you want to become a cave-diving scientist, Iliffe's the man to learn it from," says Michael Garman,
a doctoral student-to-be at the University of South Florida who, with his wife, Sherry, joined Iliffe on
the Mérida trip. "He pretty much invented the field. If you don't think so, just try and find a significant
academic paper on cave diving that isn't either by Iliffe or cites him."
Or try to find a cave diver who doesn't know Iliffe. So well-connected is he that he's joined at some point
on most of his trips by a diver considered "the Jacques Cousteau" of that country. All Iliffe has to
do is pop into a dive shop near a cave, and he has the run of it.
Iliffe's cave-diving trips have taken him to most of the world's important, known cave systems. Besides Mexico
and Bermuda, he's dived caves in Hawaii, the Galaápagos Islands, the Canary Islands, Spain's Balearic Islands,
Iceland, Jamaica, Cuba, the Bahamas, Yugoslavia, the Philippines, Thailand and a host of South Pacific islands.
Only the caves of Ascension Island, western Australia, the Netherlands Antilles and the Dominican Republic have
eluded him so far.
Sometimes, the cave's lessons aren't just scientific. The South Pacific caves showed, for instance, the degree
to which cultural myths endure. Iliffe's team was prevented from diving one cave until members showed local leaders
that the waters they viewed as sacred and not to be spoiled by divers were being pelted with bat guano behind a
rock formation. In the Philippines, a village elder hired to take divers to caves so revered them that he steered
the team away from the site.
In other ways, too, South Pacific caves provide examples of different cultural beliefs and practices. Because
the surrounding land is so rocky, many caves are used as burial chambers, a sight Iliffe admits is "kind of
spooky." Others are routinely raided for birds' nests, whose perceived aphrodisiac qualities bring top prices
Insufficiently funded by government grants, Iliffe's globe-trotting trips are invariably done on a shoestring.
In Mérida, he and his students shared cramped lodging in the cheapest of hotels and strung up a hammock
for a different member of the team to sleep in each night. Meals averaged about $3, and the group did few tourist
"Why should we?" asks Christi Daniels, a research assistant at Texas A&M-Galveston who graduated
in June and is considering graduate school. "You can go on more dive trips this way."
Cave divers tend to be a hardy lot. Just to become fully certified, Daniels and fellow student Michael Loeffler
traveled to Ginny Springs in northern Florida, home of the United States' longest underwater caves. There, a local
dive shop's four-stage, weeklong certification process progresses from cavern to cave and culminates in the teacher
removing students' scuba equipment piece by piece, then spinning and flipping them around to see how well they
reorient themselves in the enclosed, pitch-black environment. Most students drop out before then.
Iliffe, who teaches introductory biology, cave biology and cave diving at A&M-Galveston, says that isn't
his personal style. But he does take his cave-biology students deep into air-filled caves in Central Texas and,
to impress upon them the feeling of total darkness and the risks of caving, turns out all the lights and tells
stories about inattentive cavers who lost their way and died.
Most of Iliffe's work is less dramatic. Upon returning from a trip, he sends the animal specimens he's found
to a biologist at the British Museum. He also analyzes samples taken where salt water and fresh water come together
and documents what he finds, sometimes with the help of those who went with him. Garman, for instance, filmed the
Mérida-area cenotes and is mapping the one at Dzibilchatún.
Iliffe plans to present such information to the scientific community at a seminar on cenotes this November
in Mérida. But he will also turn over his work -- particularly concerning the environmental sensitivity
of each cenote -- to the Yucatán government, which wants to build an ecotourism industry around the
The officials have begun a program to identify cenotes whose beauty and safe diving conditions will attract
cave divers from around the world. It is a program, like many in developing countries with impressive cave systems,
that leaves Iliffe with mixed feelings even as he contributes to it.
"It's going to happen whether I participate or not," he says, noting that the caves could be just
as damaged by the neglect that comes from obscurity as the wear and pollution likely to come from popularity. "At
least I can help it happen in the best manner rather than the worst."
Iliffe is no stranger to such a role. He prepared a critical report on the pollution that a proposed Bermuda
luxury-housing complex would cause to the island's largest caves. The report contradicted the builder's environmental
assessment that it would actually protect them, and was instrumental in the project's being modified.
Iliffe had particular reason to worry about that project. The Bermuda caves, along with those of the Canary
Islands, are his favorites -- partly for sentimental reasons involving his exploration of them, partly for their
features. Their well-preserved, highly decorated formations are considered among the most beautiful in the world.
(The Canary Islands caves include one that holds the distinction of being the world's longest underwater cave formed
by volcanic activity.)
Iliffe has another reason to protect the caves -- he still has work to accomplish in them. He wants to find
answers to the questions his discoveries have raised, like whether there are cave fossils that will provide missing
links in marine evolution. And he wants to find a higher-group cave animal, something that constitutes a phylum
or kingdom, the top two classifications in the taxonomic table and the only ones he hasn't discovered yet.
Iliffe has one other hope: that more scientists follow in his footsteps and take up the exploration of caves.
There are a couple of cave-diving scientists in the United States and a couple in Europe, but still not enough,
Iliffe worries, to bring the field into the mainstream any time soon.
Iliffe knows scientific cave diving is an acquired taste --and not just among marine biologists. Despite already
having a worldwide reputation among cave biologists, he came to Texas A&M-Galveston nearly 10 years ago as
a mere lecturer, had to slowly carve out his own niche and received tenure only last year.
"It's been a long road," says Iliffe, a Pennsylvania boy now settled in Galveston. "But at least
I've reached the point where colleagues don't think my grant proposals are just excuses to go to the tropics for
Todd Ackerman is a Chronicle reporter. Tim Stamm is a free-lance photographer based in Naples, Fla.