Exploring the world’s deepest caves is often described as the subterranean equivalent of climbing the highest mountains. It’s an apt comparison, as there are more than a few similarities between speleological expeditions and high altitude mountaineering. Both typically require vertical climbing, for instance, and both manifest the ever-present threat of falling to one’s death, being crushed by rock (or ice), or getting swept away by a flash flood (or avalanche). But if anything, venturing deep below the earth’s surface is even more stressful, because caves are invariably dark, wet, and drafty. (Imagine being sequestered in a pitch-black room, soaking wet, with an air-conditioner blowing on you, for days or weeks at a time.) And caves are often deafeningly loud. (Imagine the sound of a thundering waterfall confined to an enclosed space.) Never mind the often unseen threats—rabid bats, venomous snakes, fist-sized spiders, and microbes that cause horrific afflictions like histoplasmosis and leishmaniasis.
Of course, none of the above has deterred the world’s elite cavers from attempting to find—and reach—the bottom of these caves. American Bill Stone, a structural engineer, spent years exploring and mapping in southern Mexico before establishing Cheve (CHAY-vay, 4,869 feet) as the deepest cave in North America. Then in October 2004, Ukranian Alexander Klimchouk, who holds a doctorate in hydrogeology, reached the dry bottom of the world (6,825 feet) inside Krubera (KRU-bera), which is found within the Arabika Massif in the western Caucasus Mountains, in a region of Abkhazia in southeastern Republic of Georgia. (In August 2006, Ukranian cave diver Gennadiy Samokhin reached Krubera’s ultimate depth of 7,188 feet.)
Last week I interviewed James M. Tabor, author of the best-selling book “Blind Descent: The Quest to Discover the Deepest Place on Earth” (Random House), to discuss the ongoing race to find the world’s deepest cave, the physical and mental challenges of extreme caving, and why the unendingly patient scientists at the forefront of this endeavor haven’t received the same level of attention and accolades as other going-where-no-one-has-gone-before adventurers.
“Extreme cavers have to deal with more failure than just about anybody else,” quipped Tabor at the outset of our discussion, noting that nine of ten cave passages are ultimately blocked by breakdown or boulder chokes—or simply come to a dead end. “Cavers have to be the most persistent bastards,” he contends, “as they’re the only explorers who don’t know what the next ten yards will look like, because there’s no way to get any advance imagery.”
What is the definition of a supercave?
I coined the term because I thought big, big caves deserved their own label. Having done some mountaineering and being a lover of mountaineering literature, I knew that there’s a special category of peaks referred to as eight thousanders—the 14 mountains that are more than eight thousand meters [26,247 feet] high. As I researched “Blind Descent,” I realized that there are maybe half a dozen caves that are close to or more than a vertical mile deep. There’s Krubera, the deepest of all; there’s Cheve and Huautla in southern Mexico; and there’s Lamprechtsofen in Austria and Aladaglar in Turkey. They may have discovered one in China but the jury is still out. So supercaves are even rarer than eight thousanders.
What’s it like in one of these caves?
The expeditions I wrote about took place in 2004 and I didn’t discover them until 2007, but I have been in some big caves in TAG [Tennessee, Alabama, and Georgia], an international caving Mecca. The first thing you become acutely aware of in a big cave is the darkness. After a while it seems to have a palpable presence.
Another thing is that these caves are wet and noisy. There is almost always water flowing alongside the routes, and the water courses can be immense. There are 150-foot waterfalls in Cheve. And Bill Stone has described the noise from one particular waterfall in Huautla as being like standing next to a jetliner, and not being able to get away from it.
Finally, supercaves tend to be characterized by vast open spaces. There are chambers in Cheve that could hold fifty diesel locomotives. The immensity of the spaces is counterintuitive.
I understand these caves can also be quite windy.
Most people think caves are dead holes, but they are alive in many ways. For one, they breathe. There are pressure changes at the surface, and as the pressure increases it forces air down into the cave, so it’s inhaling, as it were. When the surface pressure decreases, that cave starts to exhale. They have clocked the exhalations at Lechugilla cave in New Mexico at over sixty miles per hour. So they can really roar.
What are the main differences between Cheve and Krubera?
The first and most immediately noticeable difference is shape. Cheve is shaped like a giant L. The vertical shaft is about 3,000 feet deep and roughly two miles of passages are required to get to the bottom. The remainder is a long, gradually sloping passage that goes on for another two miles and drops roughly 2,000 feet. It’s also a relatively warm cave. The air temperature ranges from 47 degrees Fahrenheit at its entrance to the low 50s down deep, and the water temperatures are about the same.
Krubera is like a gigantic elevator shaft. Ninety percent of its descent terrain is technical, meaning the cavers are on rope descending or ascending. At 7,188 feet, you could stack seven Empire State Buildings within the depth that Krubera represents. It’s also murderously cold. The water is never much more than 32 degrees and the air temperature in summer is 34-36 degrees. Many expeditions prefer to climb there in winter because there is less chance of flash flooding, but then the air temperature is about zero degrees Fahrenheit and the wind chill remains below zero.
What kind of physical demands are made on extreme cavers?
Cavers not only have to contend with the climbs and the extreme verticality, they have to deal with constant absolute darkness. Unless they are moving or performing a task they turn off their lights to save battery power, so most of the time they are in the dark. They are always wet and cold and there is always a high level of anxiety. They typically lose a pound or a pound-and-a-half a day, in part because of the kind of physical work that is required—descending or rappelling with very heavy loads, and ascending the same way. In Krubera, cavers are underground for up to a month.
What are the effects of prolonged absolute darkness?
There are several that have been studied scientifically. One effect is that it disrupts normal circadian rhythms. Cavers may work for twenty-four hours at a stretch and then sleep for twenty or twenty-four hours. Second, their immune systems really take a beating without sunlight or natural light. Stone told me that after he had been underground in Cheve for two weeks, every one of his fingernails became infected with staphyloccocus.
Another thing is that each human brain has a unique tolerance for darkness. Some individuals reach their limit after a certain number of days or certain number of feet below the surface, and then they have an attack called The Rapture, which is like a panic attack on speed. I’ve interviewed people who’ve experienced it and they say it’s like a panic attack but multiplied a hundred times in intensity.
Is there a caving equivalent of high altitude mountaineering’s “death zone”?
I know what you’re referring to—that special area above 26,000 feet [where the air is so thin it is not life-sustaining]. There are two crucially dangerous things about supercave exploration. One is that you frequently have to change from one descent rope to another while hanging from a vertical wall. Two of the deaths and one of the serious injuries I describe in the book happened because of rebelays.
The other thing is the scuba diving. Three of the deaths associated with Stone’s expeditions to Cheve and Huautla were diving deaths. There is no more dangerous form of exploration than cave diving, and when you do it in an environment where there is no chance of rescue it amps up the risk an order of magnitude. I would say that the death zones in caves are the sumps—the flooded tunnels and passageways that require very sophisticated scuba diving to pass through.
Another challenge is that cavers aren’t able to communicate with the surface, correct?
That’s another thing that is uniquely unpleasant about deep cave exploration. We have deep sea vehicles that can rescue submariners thousands of feet beneath the surface. And in May 2005, a French test pilot [Didier Delsalle] landed a helicopter on the summit of Mount Everest, so if conditions are right, you can now be helicoptered off even the highest mountains. But there is no rescue in a cave. If you get in trouble five thousand feet down and four miles from the surface, you either work it out on your own or you die.
One expedition did attempt to string a telephone line down into Krubera, yes?
You can do that as long as you have a relatively free route. The line you are referring to went down about a thousand feet. But lightning struck the communications center on the surface and the charge almost killed a Russian caver [Ilya Zharkov] who was talking on the phone at the other end.
What technological developments have helped advance extreme caving?
There is so much vertical work in caving that you cannot use lightweight rappel hardware like mountain climbers do. The first big development came in the 1960s, when a southerner [John Cole] invented what cavers now call the rappel rack—essentially a supersized, beefed up rappelling device that has enabled cavers to do seven-hundred-foot free vertical drops on slick, muddy ropes, and still have control.
But by the late 1980s cavers had reached the limits of traditional open circuit scuba equipment in terms of deep caves, because there were only so many of those forty-five pound tanks that one could carry down. So Stone decided to create a rebreather, which allows a diver to re-breathe his or her own breath. It took him ten years to develop one in his home laboratory, and the model that he invented is now being marketed [for recreational use] by a company called Poseidon, which is headquartered in Sweden. The Poseidon Rebreather [Discovery MKVI] weighs about forty pounds fully charged and gives a diver eight to twelve hours of continuous time underwater. Stone remained underwater for twenty-four hours with a prototype, and the only problem he had was staying awake.
Stone might have failed in his quest to find the world’s deepest cave, but his impact and legacy seems likely to be much greater than that of Alexander Klimchouk.
I could not agree more. There’s the rebreather, but I also think we have not seen the last of Stone. For almost eight years he has been working on a NASA-sponsored program called ENDURANCE [Environmentally Non-Disturbing Under-ice Robotic ANtarctiC Explorer]. [Stone Aerospace] has built a big orange robot that looks like a flyer saucer and is about the size of a Volkswagen, which NASA plans to fly to Jupiter’s moon Europa, where it will land and melt its way down through Europa’s icecap, then drop down into the water ocean that they believe is beneath, and send information back to Earth. In 2009, they tested it [on Lake Bonney] in Antarctica. In addition to cave exploration, Stone may one day be remembered as a space explorer.
Since we’ve discussed Stone, tell me about Klimchouk.
Klimchouk’s focus has been more single-mindedly on cave exploration—finding deep caves and exploring them to their very bottom. He is particularly interested in the hydrogeology of these caves—aquifers in particular, including how they are formed, how they are polluted, and how to prevent them from becoming polluted. His legacy is going to more as a classical speleologist.
Have either Stone’s or Klimchouk’s teams made any important scientific discoveries during their cave explorations?
One of the things that is coming out of deep caves like the ones Stone and Klimchouk have opened up are life forms called extremophiles, which in the laboratory are giving birth to new families of antibiotics that are proving effective against MRSA and some of the really vicious drug-resistant bugs. I liken Stone and Klimchouk to Buzz Aldrin and Neil Armstrong—the forerunners who open a virgin, alien environment and prove that humans can get there. Some hard science comes out of what they do, but they are effectively opening the way for others to come behind them.
Why haven’t cave explorers received as much media attention as mountaineers have enjoyed?
I’ve identified several reasons. First, we have spectacular mountaineering pictures going back as far as the 1920s. But until very recently we haven’t had pictures from deep in supercaves because we haven’t had the cameras and batteries that could withstand the beating.
Another factor is that cavers tend to be a secretive group and aren’t all that fond of publicity. There’s a reason for that. It’s much easier for untrained people to find a cave and get in serious trouble than it is for someone to get on Mount Everest, for example. So cavers tend to keep caving and their activities out of the limelight by choice.
Another part of it is that caving is dark, wet, and dirty. It’s a PR person’s nightmare, and hasn’t lent itself to the same kind of exposure that mountain climbers, divers, and astronauts more easily generate. But next year James Cameron [Avatar, Titanic] is releasing a feature film [Sanctum 3D] about extreme cavers.
What surprised you most when researching “Blind Descent”?
The immense scope and scale of the supercave expeditions; they make Himalayan mountaineering expeditions seem small in comparison. Not only do they cost hundreds of thousands of dollars, they require keeping scores of highly skilled people on site for months at a time. And as I mentioned, climbers are underground for up to a month, so the time on technical, dangerous terrain is triple or quadruple [that of high altitude mountaineering]. I had no idea how much was involved and required to get down into and back out of one of these caves.
What are the chances that an even deeper cave will be discovered in the next decade or so?
Those who have devoted their lives to researching the Mexican caves claim that Krubera is by no means the Mount Everest of caves. I did two and a half years of research for the book and talked to geologists who had no vested interest one way or the other. My considered opinion is that Krubera is not going to be bested.