Photo credit: Strainu / Wikimedia Commons
An underground lake in Salina Turda, Romania, was first used to extract salt in the Middle Ages (its first documented use was in 1075) up until the early part of the 20th Century. Since 1992 it’s been open as a tourist attraction where you can descend 400 feet into the beautifully lit depths to see the stunning subterranean lake or indulge in the scientifically questionable alternative treatment of halotherapy—mineral salt baths. There’s even a floating theme park on the lake today.
