The Lost Sea: Second Largest Underground Lake

The second largest non-subglacial underground lake in the world is located in Tennessee’s Craighead Caverns. The lake, which has been dubbed “The Lost Sea,” sits in a system of subterranean caves in the town of Sweetwater.

The water body currently serves as a tourist attraction, bringing in folks from near and far who want to see it. Perhaps the most striking fact about this lake is that nobody knows how deep it truly is. But there is likewise substantial mystery about how The Lost Sea was discovered in the first place.

According to legend, a 13-year-old boy named Ben Sands found the lake in 1905 after he went exploring in the caves. After sands had wiggled his way through a tiny, muddy opening about 300 feet underground, the young boy found himself in a massive room full of water.

The cave he had found, in fact, was so large that light from his flashlight was swallowed up by the darkness long before it could reach the cave’s far wall or the ceiling. The boy wanted to know how far the water went, so he threw mud balls in every direction. But he heard nothing but splashes all around.

Since the discovery, there hasn’t been much scientific exploration take place. Yet there have been diving operations in the system that added another 1,500 feet of known depth to just one of the lake’s underwater passages.

Divers involved describe the harrowing conditions under which they attempted to chart exactly how deep the passage was. At the entrance of the underwater section, water clarity was good but diminished due to falling silt caused by air bubbles the diving team released. As the explorers went further, conditions got more hazardous as larger chunks of sediment began to break free.

In that expedition, which lasted nearly two years, divers found anthodite-like structures underwater. Also known as “cave flowers,” these formations don’t typically occur in water.

The Lost Sea’s water temperature is a stable 54 degrees. Above water, its visual extent is 800 feet long and 220 feet wide. Below, its full extent remains unknown. Its water has been stocked with rainbow trout, but fishing is not permitted.

Featured Image: The Lost Sea, an underground, non-subglacial lake located in Sweetwater, Tenn. that is the world’s second largest. (Credit: Cameron Cech via The Lost Sea Adventure Facebook page)

Have you ever visited The Lost Sea? Know of any other large underground lakes we should feature? Please consider leaving a comment to share your thoughts!