Deep South

Hard-core cavers in three southern states stop at nothing to probe an underworld wilderness.

This story appears in the June 2009 issue of National Geographic magazine.

The Goat is squeezıng through the Sphincter.

Groaning and clawing, neck twisted, white head scraping against the rock. To cram his body through this basketball-size hole requires yoga-like contortions—arms overhead as if diving, hips uncomfortably twisted the opposite of chest, legs cramped underneath. The Sphincter lies at the end of a kinked, intestinal tunnel, and Marion "the Goat" Smith is the last of our six-person exploratory team to wriggle through, a task he accomplishes with veteran agility and ceaseless cursing.

"Just so you know," Kristen Bobo turns to me, careful not to blind me with her headlamp, "the more Marion enjoys a cave, the more he cusses." Bobo, 38, is a master caver herself. Small as a child but strong as a miner, with big doe eyes that belie a will as unbendable as angle iron, she slithers through the Sphincter easy as a snake.

The Goat plops out into the dirt and proclaims in a croaky southern drawl, "What goes down must come up," which is Smith's wry way of saying that we're hundreds of feet under the hills of Tennessee, and we'll have to pass back through the Sphincter to get home.

A historian by profession, Smith, now 62, is loose-jointed, long, and lean, with skin so white you'd think he had spent his entire life underground. Which is pretty much the case. He started spelunking in 1966 and has been caving hard nearly every week since. He has explored more than 50 miles of virgin passage, most of it on his hands and knees. Gristly, indefatigable, and garrulous, Smith has ventured into more caves than any person in America.

Resting after the wrestling match with the squeeze, we switch off our headlamps to save battery life. A palpable blackness envelops us. Surface people never experience such impenetrable darkness. Up on the fair skin of the planet, even in the dead of night, there's always some light coming from somewhere. Starlight or moonlight or firelight or a wedge of kitchen light beneath the bedroom door. Eyes adjust. But not inside the stygian colon of the Earth. Here the darkness is so thick you can hold your hand an inch from your face as long as you like and you won't see it. This is an ancient, undisturbed darkness, a darkness that has been here since the dawn of the world.

We are in a newly discovered branch of Jaguar Cave, a maze of mad plumbing doglegging down through a thick layer of limestone beneath the farms and wooded ridges of north-central Tennessee. As pocked with holes as Swiss cheese, Tennessee is part of what cavers refer to as TAG, an acronym for Tennessee-Alabama-Georgia. These three states compose the southern end of a belt of limestone laid down hundreds of millions of years ago when the region was covered by an ancient sea. Where there's limestone there are bound to be caves, because limestone is susceptible to corrosion by slightly acidic water. Over millions of years this slow dissolution has riddled the bedrock with tunnels and chambers, creating a subterranean world in which the potential for exploration is almost limitless. There are more than 14,000 known caves in TAG—9,200 in Tennessee, 4,800 in Alabama, and 600 in Georgia—and there is a subculture of single-minded cavers eager to probe them all.

Hard-core cavers in three southern states stop at nothing to probe an underworld wilderness.

People have been exploring Jaguar Cave since prehistoric times, but the system is so vast that unknown conduits and million-year-old piping are still being discovered. Moving again, we crawl and climb and pull and push, eventually peeping out into a large cavern. Smith has a saying that "caves either drop, pop, or stop." This one pops. Even with our headlamps on high beam we can barely make out the walls around us. The chamber is the size of a small but very high-ceilinged gymnasium.

"Look up and right," directs Bobo. As we shine our headlamps onto a wet rock wall, a rope appears, dangling out of the upper blackness. One by one we ascend the rope. At the apex of the domed cavern we traverse along a sloping ledge over the invisible seven-story drop we've just climbed, then enter another tunnel. It's large enough that we can stand up and walk for more than a thousand feet before the passage is solidly plugged by a pile of boulders and dirt—a breakdown, where the ceiling has collapsed.

This is as far as any human has probed. Our team believes the passage continues on the other side of the breakdown, so our goal is to "push" the cave: Go beyond what is known into the invisible unknown. We divide into two parties, mappers and diggers. Smith and Bobo will survey the borehole; I volunteer to be a digger.

When it's my turn, I lie down on my belly and shimmy to the end of a hole beneath the breakdown. Flat on my stomach, the ceiling pressing down on my neck, walls forcing in on the sides, I hold the shovel stretched out in front of me and furiously jab at the dirt wall. Chunks of earth fall all around me as I dig like a berserk badger. Several times I fill a drag tray, pushing it beneath me and then backward with frog kicks, where it is emptied by the other cavers. But soon the hole is too narrow, and I dispense with the drag tray, instead using my hands as scoops to maneuver the dirt around my body.

After 30 minutes I've moved perhaps five feet forward, my arms are aching, and I'm soaked in sweat. I'm about to back out when my shovel breaks through. I feverishly round out the hole and cram my head through. There is a low, triangle-shaped crawlway ahead of me. Surging with adrenaline, I try dragging myself into this new passage, but my chest gets stuck.

From the beginning I have been hyperfocused on digging in order to stave off dark, horrifying feelings of claustrophobia. But now, stuck like a rat in the throat of a snake, a sickly anxiousness sweeps over me. I violently kick my legs, but to no avail: I'm swimming in dirt. I realize that by not using the drag tray to remove the dirt, I've buried myself.

I try to calm my racing thoughts, but my mind is preoccupied with the millions of tons of rock above me. I've been told that caves seldom collapse, and yet here I am, trapped at the bottom of a breakdown, in a cave that obviously did collapse. I try to slow my frantic breathing because I've also been told that hyperventilating expands one's lungs and only tightens the squeeze, which is exactly what's happening. Suddenly I'm thrashing shamelessly, kicking and clawing and writhing. I manage to knock off my headlamp, and everything goes black.

Cavers aren't like you and me. "I don't get claustrophobia," Kristen Bobo explains. It is twilight, and we're seated in wooden rocking chairs on her lush backyard lawn in Cooke­ville, Tennessee. "In fact, I'm very comfortable with a wall six inches or less in front of my face." Bobo, five feet four and 102 pounds, won the "squeeze box" competition in her age and weight class three years in a row. A fixture at caving festivals (bacchanals famous for cheap beer and champion bonfires), the squeeze box looks like a medieval torture device. Two sheets of plywood are placed one on top of the other like a sandwich, with the space in between adjusted in quarter-inch increments. Bobo can slide through a six-and-a-quarter-inch space.

Despite wearing a helmet, gloves, elbow pads, shin pads, kneepads, and a reinforced nylon suit, Bobo is covered with scrapes and bruises from our journey into Jaguar Cave. "That's the normal state of affairs," she says dismissively. "Cavers are too obsessed to worry about such trivial things. We all just want to go right back underground. We call it cave fever. You can see it in our eyes—a certain glow."

Bobo has explored more than 700 caves. In the process she has broken her back, torn muscles, snapped fingers and toes, and almost died from hypothermia. But what really hurts Bobo is when a cave is injured. In 2001 she visited a cave where the stalactites and stalagmites had been wantonly broken off.

"Hundreds and hundreds of formations that had taken a million years to form, destroyed. I looked around and was just overcome. I sat down and sobbed. For some reason man has the need to destroy things," she says with genuine sorrow. "Rare, very sensitive species not found anywhere else in the world live in the microclimates of caves. And there is archaeology! Like what we saw in Jaguar Cave."

We had entered the system through a secret hole high in the forest, rappelling 32 feet. After the rappel we slid down a jagged gully into the first of dozens of passageways, then followed the course of a swift underground river. As we moved along in a foot of water, Bobo pointed out the fauna: a cave cricket, pale and angular as a skeleton; a cave fish, an inch-long, pure white ghost; a slimy salamander, black as coal and covered in mucus.

In a large river passage with sandy banks on both sides, we examined prehistoric jaguar prints left by two animals as long ago as 35,000 years when they became trapped. Even more remarkable, 274 ancient human footprints have been discovered in a part of the cave called Aborigine Avenue, which is now closed to explorers. Dated at 4,500 years old, they are the oldest human cave prints in North America.

Sure enough, more recent visitors had also left their mark. Even though the ancient jaguar tracks had been surrounded by survey tape and stones, someone had intentionally tromped right through, obliterating most of them. The cave's main entrance is now barred by a massive steel gate—the first one Bobo helped to build. Her 2001 epiphany—that caves need protection—altered the course of her life. She enrolled in welding school, then apprenticed with Roy Powers, a pioneering cave-gate designer. Today she is one of the leading cave-gate builders in the United States. Commissioned by state and federal conservation agencies, Bobo has built more than 50 cave gates, including the largest in the world, a steel barrier 84 feet wide by 32 feet high that spanned the entrance to Rocheport Cave in Boone County, Missouri, until it was destroyed in a flood a few years ago.

Bobo and her fellow TAG cavers are the equivalent of the climbers in Yosemite National Park: In the 1960s both groups developed skills and equipment that rocketed their recreation into a new realm of difficulty and danger. Marion Smith is one of the original TAG cavers. He freely admits that caving has not just been his pastime, it's been his life. Over the decades, he has explored more than 6,500 caves and kept meticulous records of them all.

Smith lives on Bone Cave Road in Rock Island, Tennessee. Ten caves are within walking distance of his home. "'At's why I moved here," he tells me the first time we meet. We settle in on his front porch, drink lemonade, and he talks without stopping about caves and caving. During his monologue I notice a green nylon loop around his ankle. Smith is barefoot, and it's evident that the loop cannot be removed.

"Call that a chicken loop," he explains, "after the coward in a group." Peering at me with liquid blue eyes over his thick, perpetually smudged glasses, Smith says that one time he got stuck in a "miserable crawlway, a big mushy mud passage that got too low for me to continue. I tried to back up, but the mud was so deep, I was just miring deeper. So I called out, 'Hey! Come in here and pull me out by my chicken loop.'"

Exploring the underworld below TAG's lush, low mountains and stream valleys is a struggle not just with rock and mud, but with water. For a lesson, Smith and two of his caving comrades take me into a wet cave with a river running through it. Heavy thunderstorms were predicted for the area. If a downpour happened to park itself over the top of us, we could be caught in a flooded cave. (In December 2007 two spelunkers in the Alum Pot cave system in Great Britain had died in exactly this scenario.) But Smith and his companions decide we should carry on. If the water starts to rise, we'll scramble to the ceiling of the highest cavern, hang out, and hope.

After three hours of traveling through passages coated in mud the color and texture of chocolate, we reach a vertical drop that requires climbing gear. No one has ever gone farther. We rig descent equipment and drop over a curtain of flowstone—the calcite substance that forms stalactites and stalagmites—into another, lower tunnel where the water and mud are deeper. Beyond lies a complex labyrinth of unexplored channels, and we set out to push to the end.

We explore perhaps 400 feet of virgin passage and come to a fissure that splits the floor. Shining our lights down through the crack, we can see water, but getting down to it will be difficult. Gung ho, I volunteer (as Smith knew I would). Chimneying, my back against one wall and knees against the other, I inelegantly slide down the crack into frigid water. My feet can't touch the bottom, so despite not having a wet suit, I'm obliged to swim. The farther I swim, the more the ceiling drops. Eventually my head is twisted sideways in a small airway. The water, black as ink, is malevolently slopping into my mouth. I go under, explore the wall with my hands to see if there is an opening, then burst back to the surface, banging my head on the ceiling, gasping for air and gulping instead.

"Guess you figured out TAG caving ain't for the weak of spirit," Smith says later, smiling like a giddy boy. "Most caves are flat out ugly, if you want to know the truth. They don't lead to grand flowstone formations or giant crystals or anything else beautiful you see in pictures. But we're always searching, and sometimes … sometimes you hit the mother lode. …" Smith's voice trails off wistfully.

In 1998 Smith made one of the greatest discoveries in TAG in a quarter century. Pushing through a painful squeeze in Rumbling Falls Cave in central Tennessee, he broke out onto the lip of emptiness. The beam of his headlamp simply disappeared into the yawning darkness.

"I started throwing rocks off the edge and counting the seconds," Smith says. "I counted at least four seconds, which meant the drop was 200 feet or better."

Although Smith and his team didn't know it at the time, they had just discovered the Rumble Room, a cavern measuring some 350 feet, floor to ceiling, and four acres in size. Comprehensive records of cave sizes don't exist, but it's no stretch to say that the Rumble Room may well be the largest such chamber in the eastern United States and the second largest in the entire country. "It's the kind of discovery a caver dreams about his whole life," says Smith.

The itch to see what no one has ever seen before, "that's the main thing for most cavers," agrees Bobo. "There are so few places left up on the surface, but down here completely unexplored wildernesses still exist."

Stuck in Jaguar Cave, I did calm down, eventually. I had no choice but to lie there and let my body go limp. My clothes were so slick with sweat I could slide inside them. With enormous effort I inched my chest forward inside my jacket and suddenly slipped into the far antechamber.

Crawling forward, I was soon stopped by another wall of dirt. I thought it was a dead end until the beam of my headlamp spotted a pinhole above me. Putting my face to the hole, I could feel air moving. Another of Smith's many caving maxims is "if it blows, it goes." I suddenly found myself digging fiendishly. I was awash with the overwhelming, visceral urge to push through and see what was on the other side—cave fever.

I hit rock immediately but managed to pull out several football-size pieces. Throwing my arms up through the hole, I twisted and turned and groaned and cursed, tore the skin on my chest and stomach, but, by God, popped out into an enormous chamber.

I was ecstatic, perhaps as much for getting through what we would eventually dub the Colonoscopy as for reaching a place no human had ever been. An hour later, with considerably more digging, the whole team made it through the Colonoscopy, and we began to properly explore the cavern. To the trained caver's eye, discoveries were everywhere: A pile of ancient bat bones. The skeleton of a prehistoric rodent. Stalactites of an unusual tubular form. An intact crinoid fossil, a seabed animal with feathery arms used for feeding.

A tiny hole beckoned at the far end of the new cavern, and Bobo, being the smallest, was eventually pushed through. We heard her screaming with delight. She had discovered helictites, pure white, spiderlike formations never before found in Jaguar Cave.

"They are utterly gorgeous," Bobo exclaimed when she reemerged from the hole. "Tiny, delicate, like rare flowers frozen in time. And …" She was trembling with excitement and obviously had something else she couldn't hold inside. I looked over at the Goat, and he had a wild gleam in his eyes, like some nocturnal animal you catch a glimpse of just beyond the campfire. He knew what Bobo was going to say.

"The cave goes! I could see a passage continuing, I just couldn't fit through the hole."