Through half a foot of powdered snow, the four of us stumbled and slid down an ancient sinkhole. The fissure at bottom, in jutting bare rock, looked tiny -- but would serve.

"You'll slip through this one easy," Dave Kolb said as pointed into the blackness. "Just swing your legs over and climb down through this crack."

This, with its 14-foot drop, was the entrance to Devil's Hole, a cave in Allegany County, Maryland. Kolb, 22, and Greg Achenbach, 24, who lead frequent caving trips for Trails East Ltd. of Rockville, had agreed to guide photographer John Taylor and me into the hole -- and, they assured us, back out.

Why folks do such things, and there are hundreds hereabouts who do, puzzles some folks who don't. Marshall Tewell's a retired car dealer whose land happens to top Devil's Hole.

IS THERE LIFE AFTER DEATH?

TRESPASS AND FIND OUT!

. . SPELUNKERS WELCOME reads a sign on the property. "I've never been underground in any way, shape or form," he boasts. "Why should I? I didn't lose anything down there." Steve Hom hopes that he doesn't either. His older sister, Washingtonian Linda Baker, is a caver nonpareil. "Fanatical isn't quite the word," says Hom, who has regularly declined her caving invitations. "She's just very dedicated to it." The tone is mournful. "And I'd feel a lot better if she did something else." Baker, who goes underground nearly every weekend, muses, "It's an interesting question: Why in the world would anybody like caving? It's cold and clammy and muddy, for one thing. But what I like about it is the sense of adventure." And a Georgia psychologist named Penny Lukin, a caver who's studied her fellows across the country, sometimes thinks about the Freudian implications. "Psychoanalytically speaking," she ventures, "it could be a return to the womb. It might be more 'oral stage' -- kind of regressive in that sense. Or maybe crawling through mud is just a return to the 'anal stage.' Young children love to play in mud, but we don't do that as adults. Except with caving, where it's highly acceptable." Then there's the spy novel Shibumi, by the pseudononymous Trevanian, who admires both caving and mystic philosophy. A crucial scene, wherein the hero hears a comrade's theory while plumbing a Basque cavern, offers a different view:

But, you protest, is it fair to say the

caver is more crazy than the moun tain climber? It is! And why? Because

the caver faces the more dangerous

friction. The climber confronts only

the frictions of his body and strength.

But the caver faces erosions of nerve

and primordial fears. The primitive

beast that lingers within man has

certain deep dreads, beyond logic, be yond intelligence. He dreads the

dark. He fears being underground,

which place he has always called the

home of evil forces. He fears being

alone. He dreads being trapped. He

fears the water from which, in an cient times, he emerged to become

Man. His most primitive nightmares

involve falling through the dark, or

wandering lost mazes of alien chaos.

And the caver -- crazy being that he

is -- volitionally chooses to face these

nightmare conditions. That is why he

is more insane than the climber, be cause the thing he risks at every mo ment is his sanity. There were no heroics at Devil's Hole. With Achenbach safely below, Kolb cinched a strap to my waist and clipped on a rope, belayed to a tree branch hanging above the crack. Besides a helmet with electric headlamp, I wore high rubber boots, several layers of old clothes and, to my regret, no gloves. The afternoon was turning bitter cold. I flipped on my lamp and, heavy with doubts, edged through the keyhole and down. Achenbach directed me to the odd foothold ("Move your right leg a little to the left") while I chimneyed between rock and hard place, trying not to slip, or tangle myself in nylon cord, or impale myself on extruding stone, or wedge my bulky helmet in a too-tight crevice. In a minute, long enough for bare hands to stiffen, I plopped into a puddle on the floor of the cave. I craned my neck toward the patch of light I'd just left behind. The sky looked bleak and puny. Taylor and Kolb lowered down provisions -- Taylor's camera box and, two at a time, four canvas cave bags of food, water, first- aid kit and candles -- and joined us in the moist gloom, a space the size of a closet. In the lamplight, the pockmarked limestone, covered with mud, glimmered in basic brown. There was a sound of dripping water, and a sickly-sweet scent of burnt carbide -- from Kolb and Achenbach's flaming lamps. The chill no longer had much bite, but mist rose off our bodies, and swirled out of our mouths when we talked. "The humidity down here's a hundred percent," Kolb said, breathing mist, "so we'll always have this steam." I wondered if it would get any warmer, and Achenbach promised it would -- once we moved away from the entrance, along a stream passage, and into the main cave. "Winter or summer, it makes no difference: The temperature's always about 55 degrees." The four of us shouldered the cave bags and, with Kolb taking the lead, climbed through another crack, half-hidden around a corner. We started our descent. With just enough room to crouch, we slid and scrambled over boulders and ridges, using them as a jagged staircase. Water trickled past our boots -- in summer, Kolb said, it rushes by in a torrent -- and mud caked our clothes. About 50 feet below the entrance, we came to a crawlway. It was a slick, sludgy tube, two feet wide and perhaps 18 inches high, but positively expansive by crawlway standards. The slightly-built Kolb went first. Kneeling at the opening, I watched the soles of his boots recede, then vanish. The sounds from within -- a couple of grunts and a few bursts of breath -- were those of mild exertion. It took him about a minute. "Okay," came his muffled yell, from the other side. I dropped to my belly and slithered in. There wasn't space enough for two arms out front, so I trailed one behind, using the other to push the cave bag ahead or claw at mud as the spirit moved. The crawl began with a slight incline and quickly leveled off. I tried at first to evade inch-deep pools -- a menacing gleam in my lamplight -- by getting up on one elbow. But in this position, all the kicking and scratching I could manage wouldn't budge me even an inch. So I went down and wallowed, twisting and kicking, propelling myself a few inches with each renewed effort. After taking several minutes to negotiate 15 feet, I popped out the other side, soaked to the bone. Next came Taylor, a man of no mean girth. With scant clearance, plus his hefty camera box to contend with, he nearly called it quits. "I can't get a purchase," he gasped at one point. "I don't think I'm coming through." "Yes, you are," Kolb insisted with a chuckle. "Just relax. You're doing fine." And soon Taylor was out, too, Achenbach on his heels. (The photographer later said, "I once was covering an Iranian demonstration and got hit by a motorcycle, but that was nothing compared to this.") We were standing in the Mud Room, a chamber aptly named. After Achenbach lit a couple of plumber's candles, enough to brighten this cozy space, Kolb broke out a bottle of punch and passed it around. Taylor and I switched off our lamps to save batteries, and our guides checked their carbide flames. We rested a bit, nibbling on chocolate bars and dried apricots. Much to my surprise, I was starting to fe in the absence of food. "Be careful not to touch them," Achenbach said, though neither Taylor nor I was threatening to. "If we woke them up, they might use up so much energy, they'd die." Aside from bats, caves like Devil's Hole may shelter a few hardy arthropods and perhaps some fish -- many of them albino or nearly transparent. Happily, in this part of the country, caves stay too cold for snakes. "There's really not a lot of life down here," Kolb said. The route from the Mud Room took us through a tight walkway to the Big Room, a chamber with 40-foot ceiling and balcony, and upward into the Turtle Room, named for the whimsical mud sculpture set atop a stone. A caver molded it years ago, and those who followed him loved it and left it. Sitting beside the turtle, we doused our lights to commune with utter darkness. Red wheels, mind-made, turned before my eyes. I closed them and opened them, but the wheels still whirled. Achenbach said, "Your eyes will never adjust." Kolb talked of troglodytes and things that go bump in a cave. Through another walkway, and across another stream, we trekked to the Flowstone Room. It's the only chamber in Devil's Hole -- so small it can handle but two people at once -- with such formations as flowstones, stalactites, rimstone dams, soda straws, and bacon rind. These were more delicate than breath-taking, and certainly not the stuff of Hollywood caves. We looked but didn't touch: a smudge of mud can stop a stalactite, which drops from the ceiling about a centimeter per century. From the Flowstone Room, it was back past the second stream, where Kolb pointed out patches of cave coral and cave popcorn, and up into Fat Man's Misery, a passageway tighter than most. We edged through sideways at a backward tilt, the temperature dropping as we climbed. A sharp right turn, and we stepped across a 10-foot chasm -- where Kolb kindly served as a human bridge, so Taylor and I could tread on his toes -- and into the main stream passage. There were a few more scrambles and we arrived at the escape hatch. Peering up through the crack, 14 feet above, I realized I'd lost track of time. It had taken three hours to explore a mile of cave -- Achenbach checked his waterproof watch -- and now the night was well along. Cold and soggy, I wasn't looking forward to the final push. Kolb went first, scrambling up and out in no time and dropping the rope for Taylor. He clipped it on and gamely started upward. He surfaced ten minutes later. (Kolb and Achenbach shouted encouragement; I shivered in silence.) Now it was my turn. "Remember," Achenbach said as I prepared to go on belay. "Climb straight up, then swing over. If you climb off to one side you'll just get stuck." I thanked him and started. By the time I'd climbed three feet off the floor, the feeling was leaving my hands. Numbly, I grabbed at ridges and struggled for toeholds, trying to follow Achenbach's running instructions. After a while -- an eternity perhaps -- I began to make some headway. Finally I reached the top of the chasm. Bringing knees to chest in fetal form, and spending the last of my reserves, I pushed myself into the outside world with a groan. I lay on the ground a while before getting up. "It's just like being born, isn't it?" Kolb said. I nodded and wandered off, starting up the wrong side of the sinkhole and falling down in the snow before Kolb pointed me toward the car. He told me later, as we devoured dinner at a roadside restaurant, drained yet quickened by the day, "You seemed sort of incoherent and disoriented for a while there, the symptoms of hypothe exploring the unexplored, and sharing among themselves the fragile beauty below the surface. "Take only pictures, leave only footprints, kill nothing but time," goes the motto of the National Speleological Society, the ecology-conscious group of some 5,000 people who account for organized caving in the United States. "We're not out to recruit new members, and we don't go out of our way to popularize the sport," says Paul Stevens, an electrical engineer for the Navy who serves as executive vice president of the speological society. "There's a feeling that the cave resource is very limited, and we should do our best to protect it." Still, many cavers find it hard to contain their enthusiasm, even to the point of making up tunes about it. The chorus to "Underground Expressway," by a Virginia caving troubador named Dave Foster, goes:

Singin' Goodnight America,

How could you

Miss the opportunities you've had?

We'll be underneath your fruited

plains till morning, While the rest of you are home safe in bed. The song could have been written about Linda Baker, the Washington native who worries her brother. Baker, 32, plunged into caving seven years ago -- literally, down a 160-foot chasm called Hell Hole in West Virginia. "I was a little bit nervous going down and even more coming up," says Baker, who worked at the White House until the last change of occupants, and now makes maps of newly explored caves. (At 5f4i and 110 pounds, she can fit through crawlways eight inches high.) "The most rapelling I'd ever done was two days before, when I hung a rope in a tree in the back yard of my apartment building. Then I tried this cave. I was lucky to have gotten away with it. "I suppose you know that one of the serious caver's big dreams is to explore virgin cave, where no human footsteps have ever trod before. That's always in the back of the serious caver's mind. It's a pioneering spirit, like the pioneers who went westward in this country. Whenever I've been in a virgin cave, where I know I'm the first person in a particular place, it's always been a strange feeling, and very exciting. "We -- I mean cavers -- often tell ourselves that we're all masochists. We get bruised and sore, muddy and cold and wet. And we constantly do this. I've been in water up to my neck for 18 hours, trying to map a cave system, absolutely miserable. I remember there were three of us, lying on sleeping bags after a 20-hour trip, vowing to one another that we'd never go back in. All of us thinking how bad this is, and why are we doing this? "It does work on your mind, and it's physically very challenging -- the physical and mental challenge of me against an alien environment. To see if you can explore and come through it all together. There've been lots of times when I've been underground for as long as 40 hours. "Being underground does have a way of instilling a bit of fear in people. I know it does with me. I have a dread of insects, spiders, cave crickets -- masses of them hanging over my head. Maybe that's why I like it. Subconsciously, I know there's fear, so I try to overcome it, and there's a sense of accomplishment in overcoming something in myself. "There are a lot of unforeseen things. Three years ago, there were five of us in the Friar's Hole System in West Virginia, all experienced cavers, and one member of the group was climbing up a narrow crevice on a rope. He wasn't managing very well, so he decided to come back down to redo his vertical equipment. He was an excellent caver. He started down, and his helmet wedged in a crevice. He strangled on his chin strap. We had to wait five hours for help. After the emotional trauma, I couldn't go back into a cave right away. I waited. I think I took my next trip 10 days later. "It's like falling off a horse. You should immediately get back on." SOME INS AND OUTS OF CAVING Here are some people to call to find out about caving activities in the WashonsI chimneyed between rockington area: POTOMAC SPELEOLOGICAL CLUB: Linda Baker, 703/560-5412. D.C. GROTTO: Dick McGill, 301/894-3795. SLIGO GROTTO: Lisa Green, 301/972-1735. To find out about Trails East's caving trips, call 301/251-0131.