SWEETWATER, Tenn. (WATE) — The Lost Sea was first developed as a tourist destination in 1915. It is considered to be the country’s largest underground lake, and the history of The Lost Sea can date back to prehistoric times.

The attraction’s website refers to a giant jaguar that once roamed the caves 20,000 years ago. The animal was apparently lost in the caves and is thought to have wandered for days before plunging into a crevice. Its bones were discovered in 1939 and some are on display in the American Museum of Natural History in New York. Plaster casts of its tracks along with other bones are displayed in the visitor center of the Lost Sea.

The caverns, located in Sweetwater, hold a deep history in East Tennessee. Once popular with the Cherokee, the area’s first white settlers used the caves as an area to store food as the temperature is a constant 58 degrees. The site’s website also shared that during the Civil War, the Confederate Army mined the cave for saltpeter which is used to make gunpowder.

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The lake was first discovered in 1905 by 13-year-old Ben Sands and its full extent is not known. It is about 144 feet below the surface and is fed by four underground springs covering around 4 and a half acres. The caves themselves, according to thelostsea.com, are a “part of an extensive and historic cave system called Craighead Caverns.” If you would like to check out the caves for yourself, click on the link above for more information.