Imagine a clear alpine stream rushing through a beautiful, primitive mountain range, the sort of icy, frothing scene you see in a beer commercial. Now picture a two-foot hole opening in the streambed, an unexpected rip in the mountain's limestone skin that sucks the stream under like bathwater rushing down a drain. Seven miles away, 1,800 vertical feet nearer to sea level, just as unexpectedly the stream reappears, shooting out of a mossy rock wall with the power of an open city hydrant. Finally, put yourself somewhere beneath those seven missing miles of stream-bed, slithering along in the near-freezing water, snatching desperate breaths from the few inches of airspace between you and the hundreds of tons of rock overhead.
That should give you a pretty good idea of where I am.
Ahead of me in the two-foot-diameter tunnel are the boots of Sheri Engler. I assume that the rest of Engler is attached to the boots and that two other cavers are still in the passage ahead of her. But that's pretty much guesswork: The carbide miner's lamp mounted on my helmet has just been put out by a wave. Somewhere beyond the cavers are silent, enormous chambers, sparkling waterfalls and coal-black fossils that the stream has passed on its way to dousing my lamp.
The water seems a living, angry thing. It wants me out. If I let go of the submerged cracks and stone nubs my cold-deadened fingers cling to, I'll shoot backwards, losing the hundred feet of crawl I've gained. The surrounding rock is a brilliant white dolomite, a limestone containing large amounts of magnesium, the main ingredient of the mythological philosophers' stone and of laxatives. The dolomite also holds thousands of wormlike fossils, the ancient burrows of tiny sea creatures. These fossils protrude from the floor and walls like so many straight razors, forming a surface cavers call "velcro" because of the way it snags and rips any clothing or skin that touches it.
The stream carves bizarre peaks and dips over this gleaming rock meringue. I can breathe well enough by turning my head sideways. But breathing is not the only issue; I must make some progress along this crawl quickly. Although this is potentially one of the country's deepest caves in relation to the surface overhead, I am still 7,500 feet above sea level, where the snow-fed current remains a constant 39° F. Unless I move soon, the giddiness of hypothermia will set in, quickly followed by oppressive fatigue and a sleepy death. Pete Shifflett, the world-class caver who—with 13 crossings—knows this passage better than anyone, has warned: "If you stop in there, you die. Period." So I stare at Engler's immobile boots by the dim light of a lithium-powered backup lamp, wondering what has caused them to become immobile. There's no point in trying to shout over the roar of water. Already cold seeps into my wet suit.
This passage—seen by only 15 people since its discovery in 1980—is called the Grim Crawl of Death. The name makes it sound entirely too pleasant. It is a 1,000-foot tube located in Wyoming's Bighorn Mountains, in a cave called Great Expectations, and I am here by choice.
Somewhere in the back of every caver's mind is a little kid watching a Saturday matinee. Modern cave explorers scoff at the clichés of the typical Hollywood cavern—monsters, lost cities, glowing jewels, bats tangled in some bimbo's hair—but what lies beyond the next crawlway or at the bottom of a newfound pit still tantalizes them. The world's highest mountains, wildest rapids and steepest ski slopes are visible, and thus within the realm of comprehension—even if intimidating. But the deepest, most challenging caves are never seen in entirety, never conquered in the absolute; they remain forever open to historical revision. A common caving refrain is: "I don't do this 'because it's there.' I do this because of what's not there—yet."
Membership in the National Speleological Society recently topped 7,500 for the first time in its 46-year history; the Huntsville, Ala.-based organization expects it to rise to more than 10,000 by the middle of the next decade. That's more people scrabbling around underground than ever before, but odds are you would never recognize any of them. And it's even more unlikely that you have heard of any of the thousands of wild American caves in which they practice their sport. That's because, as Outside magazine columnist Tim Cahill puts it, "Cavers are, by and large, a closemouthed, introverted, even slightly hostile group."
With reason. Caving is unique in the way it destroys its own irreplaceable environment. A careless nudge can obliterate a latticework of crystal thousands of years old; the oil from the touch of a human hand can permanently halt the growth of a 20-foot stalactite. Even the layered mud of a virgin cave floor is noticeably changed by a single explorer's crossing.
Just gaining access to this underground wilderness can be a delicate matter. Most caves are located on privately owned land; given modern society's litigious mood, many cave owners would sooner bulldoze entrances shut than risk a day in court with the survivors of some careless caver who perished beneath their alfafa crop. So cavers carefully cultivate landowner relationships, keeping names and exact locations of the most spectacular—and potentially dangerous—caves secret from the general public. Not infrequently, caves are kept secret even from other cavers. Most NSS chapters, called grottoes, maintain one or two "sacrificial" caverns for novices, revealing more exciting, if more dangerous, caves to new members only after months of proven dedication and gained experience.