Smooth as glass and quiet as a tomb, The Lost Sea is a watery grave for carelessly dropped smart phones.

The Lost Sea

Sweetwater, Tennessee

The Lost Sea claims to be America's largest underground body of water. Fed by multiple subterranean sources, its extent is unknown, but its upper chamber has water that covers 4.5 acres at depths of 70 feet. This is a freshwater lake, not a salty sea, as countless tour-takers have corrected the Lost Sea's very patient tour guides.

Blasted out tunnel leads to The Lost Sea, bypassing a flooded passage that kept it lost.

Global Warming has had little effect on the Sea's level, but a drought can drain it. It was a drought that led to its discovery by 13-year old Ben Sands, when the water fell below the level of a connecting passage. It was lost again for 60 years (no one believed Ben) until the passage was drained by another drought. Now a blasted-out tunnel provides year-round access to the sea, and Ben (at age 73) was finally given credit and a plaque in the cave lodge.

Tour guide Kevin walked us down to the Sea and pointed out attractions along the way, such as leftovers from the cave's post-atomic-apocalypse survival stockpile (we've seen others elsewhere), and the moonshine still that was used when the cave operated as The Cavern Tavern in the 1940s. "The temperature, air pressure, and humidity allowed people to drink more than they normally could," said Kevin. "As they climbed up and out of the cave they would get drunker and drunker and pass out and fall back down."

Atomic survival supplies, unopened since the Cold War.

The Lost Sea's colony of rainbow trout will never see a rainbow.

Kevin also showed off a feature named The Devil's Hole, lit in lurid red. He said that the cave once had a tour group of 15 Wiccans, and when they reached the hole they grew nervous. "They started yelling that there was 'Too Much Power,'" Kevin recalled. "They had to leave."

The high point of any trip to The Lost Sea is the boat ride. A bucket of beef liver pellets is brought along to hurl at the Sea's population of rainbow trout. The trout are not blind cave fish; they were brought down from the surface in the hope that some would find their way back to a lake or river. The experiment failed, Kevin said, because trout can't see in the dark and because the constant supply of meat pellets gives them no incentive to leave.

Tour guide Matthew told us that he was once out on the Sea with a young couple when the man suddenly proposed to the woman. "She said no," Matthew recalled. "I had to continue the tour, out in the boat, as if nothing had happened. It was really awkward."

Walkways were built in the cave when The Lost Sea opened as an attraction in 1965.

Things do fall into The Lost Sea, occasionally people, mostly cameras and smart phones. "If it falls in, it's not coming out," said Kevin. "I remember one that fell in with the screen on; you could see it glowing down there for days." Visitors might want to wipe all embarrassing photos from their phones before sailing on The Lost Sea, in case their devices accidentally become archaeological artifacts for a future civilization.

Adults, not children, visiting The Lost Sea often ask questions that aren't in the guide manual. "One time I was asked, 'Does it snow in the cave?' recalled Kevin. Mathew said that he was asked, "Why is the cave dark?" and "Are the fish real?" Tour guide Heath was stumped by, "Why don't you move the cave closer to the interstate?"

"A lot of people ask, 'Has anybody died down here?'" said Kevin. The standard answer is, "Not that we know of," although the bones of a giant prehistoric Pleistocene Jaguar were found and are now in the Museum of Natural History in New York.

We asked Kevin if Ben Sands (1894-1976) had ever returned to the Lost Sea he had discovered. "I don't know if he ever took the tour," Kevin said, "but we really should name one of the boats for him."