03/28/2026
https://www.facebook.com/share/1CJfwujsyx/
Deep under the mountains of Tennessee lies the largest underground lake in the US...and you can tour it on a glass-bottom boat! At The Lost Sea Adventure in the small town of Sweetwater, you head far below ground to see this hidden lake tucked inside a huge cave system. Your visit begins with a guided walk through a long cave tunnel, where you pass rock walls, ceilings, and wide open rooms as you make your way down into the mountain. The path slopes deeper underground until you reach the lake, where everything opens up into a quiet, dark space. Once there, you step onto a glass-bottom boat and slowly move across the still water while large rainbow trout swim just below your feet. The guides share real history along the way, including how the cave was used by Cherokee people long ago and later by Confederate soldiers during the Civil War. The full tour lasts about an hour and fifteen minutes, and the cave stays close to 58 degrees all year, so it feels cool and steady no matter when you go.
