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.