I emerge from Fat Man's Misery--a narrow, twisted low-roofed passage where the rocks have gone shiny and smooth from the touch of countless hands reaching out for balance or perhaps solace--only to find myself just a short walk from the River Styx. The sliver of water apparent between walls of rock is green and seemingly leisurely; it imparts no sense of foreboding, no mythical beings spring to life. Yet this small river is a powerful force. This flow built one of the most extensive cave systems on earth; it sculpted limestone into the more than 360 miles of tunnels, chambers and beautiful shapes that compose Mammoth Cave.
Our group--45 enterprising people who have been soundly warned about the physical demands of our two-and-a-half-hour "Making of Mammoth" tour--has descended to the fifth and lowest level of the cave system to see the River Styx. Down here the air is humid and thick, the ground muddy in places, and the knowledge of depth, of the weight of layers of rock above us, is more oppressive than in the higher, dry realms of the cave. But it is only down here, in the potentially claustrophobia-inducing depths, that water is still at work, carving new passageways. And only here that some of the cavern's most unusual creatures--colorless Mammoth Cave shrimp, Indiana eyeless crayfish and eyeless cavefish--make their home.
This article was originally published with the title Hiking Underground.