The world is filled with hidden wonders waiting to be discovered and up until 1905, it seems that the Lost Sea in Sweetwater Tennessee was one of them. This lake is about 243 meters (800 feet) by 67 meters (220 feet) at the surface, but is so large under the water that divers have not yet been able to explore it all.

How can it be that a large lake went undiscovered for so long? Simple, it is underground in a cave system.

The cave system is called Craighead Caverns and is a very large system that had long been known. There is evidence that the Cherokee people of the area used it in the past, storing items like jewelry, weapons, pottery, and more in the cool caves. The caves are so large that many of these artifacts were located in a large chamber that is called ‘The Council Room.’ The Council Room is almost a mile from the cave’s entrance.

In the 1800’s, Europeans also found and used the cave system for storage. They primarily used it to keep vegetables and other things that would keep better due to the climate in the caves. In one part of the cave, there is the written number ‘1863’ on the wall, which is believed to have been written by a Confederate soldier.

All of these interactions with the cave system took place in the main area, but in 1905, 13-year-old Ben Sands noticed a tunnel and decided to try to climb through. This process was described by tour guide Savannah Dalton when she talked to CBS News in 2019:

“The lake was discovered by Ben Sands, a 13-year-old boy who had actually crawled through a tunnel that was the size of a bicycle tire for 40 feet before he dropped down into the lake itself and actually waded out into about knee-deep water. It was a lot smaller when he came through. But we’ve blasted it out since.”

The thought of crawling 40 feet through a crack that was so small is unimaginable, but the payoff was huge for young Sands. He found himself in a massive lake in a very large room. His torch couldn’t even illuminate the walls on either side. As far as researchers know, Sands is the first human to ever see this lake.

To try to figure out just how big the room was, Sands took mud balls and threw them in every direction to see if he could hear them hit a wall. In each attempt, he just heard the mud splash into the water.

Since his discovery, the small crack has been blasted out to allow for a much larger opening, which welcomes around 150,000 visitors each year. The area has been named a National Natural Landmark and it is believed to be the largest underground lake in all of North America. Expert divers explore the lake, which has many leads off the main lake down into other halls. They have so far mapped more than 13 acres of the water, but haven’t yet found its end. Diving in underground caverns is very dangerous, so this task is left to experts.

To see the lake for yourself, you can visit the caverns and explore them on guided tours. If you’re not in the area, check out this CBS special video on these amazing caves:

If you do happen to visit, make sure to look down into the water and see if you can find one of the 300 rainbow trout that call this cave home. They were placed in the water years ago to see if they would help people find unknown exits to the lake, but so far they have not. Due to the fact that there is very little living in the water in these caves, the fish rely on food from the workers and visitors of the cave system, so if you choose, you can buy fish food to drop into the water for the inhabitants of the lake. Dalton talked about these fish, saying:

“They’re down here long enough that they do lose a small portion of both their eyesight and their color. The lighting of course is not natural sunlight, so they can’t really maintain that pigment.”

The story of these caves, and especially this remarkable lake, is incredible and it is all thanks to the 13-year-old explorer who squeezed through the small crack in the cave wall.

This young man’s actions were risky, but they really paid off.

If you thought that was interesting, you might like to read about 50 amazing finds on Google Earth.