Thursday, September 24, 2026

Question: What underground lake near Sweetwater is the largest in the United States?

Answer: The Lost Sea. Tucked inside Craighead Caverns near Sweetwater, the Lost Sea is the largest underground lake in the United States and the second-largest in the world. A 13-year-old named Ben Sands discovered it in 1905 after squeezing through a small opening and finding the vast water below. Today visitors glide across it on glass-bottom boats, spotting giant rainbow trout in its clear depths.