Lost Sea is in Sweetwater, TN, and is the site of the world's largest underground lake. You walk very deep underground and they tell you the history of the cave. You can get on a boat and go into the lake with tour guides and see some of the fish that live in the lake. Then they turn off all the lights and show you how dark it is.
Back in the olden days, the cave was used as a bar, and something about alcohol mixing with atmosphere makes you drunker the higher above the earth you are (basically it takes more to get drunk in SC (below sea level) than in Denver (1-mi above sea level).
So all of these old timers would go down into the cave to drink and not feel drunk, but would start walking towards the exit and get stone-cold drunk and fall down the steps. I thought it was funny, and well worth the visit.
more