13-year-old Ben Sands discovered Lost Sea in Tennessee cave

In 1905, a 13-year-old boy named Ben Sands squeezed through a passage no wider than a bicycle tyre in Tennessee's Craighead Caverns and discovered a hidden underground lake. The lake, 140 feet below the surface, is now known as the Lost Sea and is the largest underground lake in the United States.

The visible lake covers about 4.5 acres and is 70 feet deep, but divers have mapped over 13 acres of water-filled chambers beyond it. The cave has evidence of Cherokee use and Confederate mining for saltpeter during the Civil War.

Today, the Lost Sea is a National Natural Landmark and a tourist attraction. The entrance Sands used has been enlarged for visitors.