Midway through the "Gunbarrel" in Knox Cave, New York, I tried to pull myself forward a little bit. There wasn't enough room, and my hand stuck in a crevice beneath me. As I pulled back to get it loose, my helmet cracked hard against the rock ceiling. Now both my arms were stretched straight in front of me, my legs straight back. The only way to get moving again in that tight space was to push myself with my boot toes, lifting myself off the ground with my elbows, gaining an inch or two each time. It was 50 feet that way. And most of the cave was still to come.

This was my third trip to a New York cave, but many of the others were beginners. I could hear them twisting through the Gunbarrel behind me, struggling even more than I had. The tube is just wide enough to squeeze into and is perfectly smooth, so you can't use the walls for leverage. There's a legend that some skinny greased marvel once slipped through in a record 23 seconds, but I was lucky to have made it in under ten minutes. My coveralls were ripped and splattered with mud; but then, that was all supposed to be part of the fun.

Fun? With these rewards, cave exploring will never be a chic sport. But its devotees measure enjoyment in inches of mud.

On Wednesday evenings, ten or twelve "cavers" (most of them avoid the term "spelunkers"), members of the Boston Grotto, the local caving club, meet in the Harvard Outing Club's quarters to brag about the caves they saw last weekend or to plan trips for the next. A few times a year they run an "easy" trip, like the one I was on.

Many people who are thinking about taking the first trip, that "easy one," don't know exactly what the trip involves. Lots of tourists, driving through Virginia of Kentucky, have stopped to visit a commercial cave. For a fee, a guide takes you in over surfaced paths that wind around electrically-lit rock formations. You could get the impression that caving is much like that, but without the lights, crowds, or the admission charge--just wandering in awe through the crystalline depths of the earth.

But after you've bounced along a washboard country road and trudged a mile through fields in upstate New York on a hot summer day, you know it isn't going to be like that at all.

Someone told you to wear old clothes, so you've scrounged around for the worst sweatshirt and dungarees you could find. Cavers usually prefer coveralls, since any tight place can pull your sweatshirt up over your head, and then your chest gets painted with mud. To protect your head you wear a miner's hard hat with a carbide light. In your pockets are stuffed a bottle of water, a spare bottle of carbide, a flashlight, matches, and a candle.

As you squeeze down into the fissure in the rocks the slot of daylight above your head narrows. Finally it blacks out completely, and only your lamp and the lamps in front of you light up the cave. But the muddy walls soak up what little glow there is, so that you can see clearly for only a dozen feet ahead. And the little circle of light shows up only dark brown on the walls and yellow in the puddles of slime. Beyond that, it's just black.

"You know this is Freudian, don't you?" one of the beginners yells.

"Yeah--back to the womb," comes the answer from up the crawlway. But it's not that at all: it's damp and cold down here, with a million tons of rock balanced over your head. In the long squeeze coming through the Gunbarrel, even an experienced caver sometimes feels a twitch of claustrophobia. Novices may have to be dragged up with a rope.

Blacker Than Night

When you're in a big group, the moving lights and the sounds of other people talking can make the cave seem to be just a dark room. But when you get off by yourself, the darkness starts to close in. A drop of water splashing down from the ceiling puts out the lamp, and no night was ever this black. Deep down the cave echoes lowly to a distant river, somewhere below. A spot of limestone drips onto the floor. You can hear the cave growing, and it can scare you.

Maybe you light a candle to find something familiar. You can't Rock is rock, but in a cave it assumes strange shapes -- hollow tubes or bursts of crystals. The fish in pools of water are eyeless and are nearly transparent. Brown bats, squeaking as they zip around you, are the most common animals. Often they carry rabies.

For many cavers, it's this gruesomely different kind of environment which makes the sport fascinating. In Ward's Cave, N.Y., one of the easiest, there may be as many as sixty people inside at one time, stumbling around each other. As soon as a new cave is discovered, the crowds head for it.

As a result, some cavers get incredibly secretive about the best places. For years rumors have circulated about a certain Garden of Eden Cave in Schoharie County, N.Y. -- a cave which is supposed to be three miles long and filled with formations--but only a handful of people know where it is, and they won't talk. The attempts to keep a new cave or tunnel's location secret sometimes go to ridiculous lengths.