Tenn-e-secrets

The Lost Sea is a living mystery.

Credit: State of Tennessee

Somewhere beneath the quiet hills of Sweetwater, a vast underground lake stretches into darkness, its edges unmapped, its depths unknown.

Known simply as The Lost Sea, this hidden body of water has fascinated explorers, scientists, and curious travelers for more than a century.

In 1905, a 13‑year‑old boy named Ben Sands discovered the lake when he crawled through a narrow tunnel approximately 300 feet underground and fell into a cavern half-filled with water. He tossed mudballs into the darkness to gauge the cavern’s size. But instead of hearing those clods hit walls, Sands only heard splashes. His discovery was later confirmed by adults during a drought that lowered water levels.

The Lost Sea is in Craighead Caverns, a limestone cave system used by the Cherokee as a council chamber. This is evidenced by artifacts like pottery, arrowheads, and jewelry found in the “Council Room” nearly a mile from the entrance.

In the Civil War, Confederate forces mined saltpeter in the caves for gunpowder. In 1915, locals decided to open the cave to the public. A dance floor was installed in one of the large upper rooms. Cockfights were held. During Prohibition, moonshiners used the cave for illicit distilling.

In 1939, the fossilized remains of a giant Pleistocene jaguar were uncovered inside the caverns. Some of those bones now reside in New York’s American Museum of Natural History, while tracks and casts remain at the Lost Sea visitor center .

The lake’s visible surface spans roughly 800 feet long and 220 feet wide (roughly 4.5 acres). Divers have mapped about 13 acres of submerged chambers but still have not charted the cavern fully. That is, no end to the lake has been found. One diver ventured into the water-filled rooms with a sonar device. He took soundings in all directions and found nothing but more water.

Today the Lost Sea holds the distinction of being the largest underground lake in the United States and the second-largest, non‑glacial underground lake in the world, after Dragon’s Breath Cave in Namibia.

Visitors can descend about 140 feet into Craighead Caverns via sloped walkways that pass through impressive limestone formations, including rare anthodites, also known as “cave flowers,” found in only a few places worldwide.

The guided tour includes a glass‑bottom boat ride across the underground lake, where guests often spot rainbow trout. (Though, no fishing is allowed.) Tours typically run year‑round (closed Thanksgiving and Christmas), lasting about 75 minutes over a three-quarter‑mile route.

The Lost Sea isn’t just a tourist attraction, it’s a living mystery. Its discovery by a curious kid in 1905, its deep ties to Native American history, war, moonshine, paleontology, and subterranean geology make it a layered story. And with vast swaths still uncharted beneath its surface, it remains one of America’s most compelling underground enigmas.