Deep inside a mountain near Sweetwater in East Tennessee is a remarkable body of water known as The Lost Sea. Listed by the Guinness Book of World Records as America’s largest underground lake, the Lost Sea is part of an extensive and historic cave system called Craighead Caverns.

Visitors are treated to a wide variety of interesting formations including several displays of rare crystalline structures called “anthodites.” These fragile, spiky clusters commonly known as “cave flowers” are found in only a few of the world’s caves. The lake is located 140 feet below the ground level so the temperature remains a pleasant 58 degrees.

The full extent of the Lost Sea is still not known despite the efforts of teams of divers armed with modern exploration equipment. The visible portion of the lake is 800 feet long by 220 feet wide.

Excursion boats powered by electric motors carry visitors onto the lake, which is stocked with some of the largest Rainbow trout in North America. Fishing, incidentally, is not permitted.

Beneath the calm waters of the four-and-a-half acre lake divers have discovered an even larger series of rooms completely filled with water. More than 13 acres of water have been mapped so far and still no end to the lake has been found. One diver ventured into the water-filled rooms with a sonar device. Hugging the wall to assure his ability to find his way back, he took soundings in all directions and found nothing but more water.