This beautiful cavern includes a 3/4-mile talk through an intricate cave system that leads a huge number of visitors and tourists to an underground lake known as the Lost Sea. Once visitors reach the lake they are able to board a flat-bottom boat and ride around on its smooth, glassy surface. There are also tours that allow visitors to spend the night in the cave and explore some of the lesser-seen parts of the enormous cavern.

The Lost Sea is known as America’s largest underground lake; it covers more than four acres. Recognized by the United States Department of the Interior as a registered National Natural Landmark, the Lost Sea at the bottom of this cavern is not just large and beautiful. It’s also unique because it contains an abundance of “cave flowers,” or rare anthodites. The lake is also stocked with some of the largest trout anywhere in North America.

The full extent of the Lost Sea is still not known despite the efforts of divers who have traveled throughout the cave system armed with modern exploration equipment. Thanks to them, though, we know that the visible portion of the lake is about 800 feet long and 220 feet wide. Beneath the calm waters of the giant lake, the adventurous divers have found a series of large rooms filled entirely with water. More than 13 total acres have been mapped so far.