In 1938, the Rummu Prison was founded at a limestone quarry in Rummu, Estonia.
Inmates at this prison camp were forced to mine limestone alongside prisoners from the Murru Soviet Prison until 1991, when the Soviet Union collapsed and Estonia regained its independence. The place was abandoned soon after, and because no one was pumping groundwater out of the quarry anymore, the ruins eventually became submerged in a new lake.
Parts of the prison can still be seen today, but some of the buildings and mining machines are completely underwater. And even though the lake bed is peppered with pieces of thick concrete, tree branches, rebar spikes, and barbed wire, people can't help but plunge right in and explore the area.
The Rummu quarry has become a very popular spot among divers and adventure seekers.
It's currently surrounded by a high wall and barbed wire, but people still manage to climb in all the time.
It isn't hard to see why they'd want to visit the old prison -- it's hauntingly beautiful, especially at night.
Some have even skated on the frozen lake during the winter and captured breathtaking videos of the ruins below the surface.video-player-present
The underwater sights are even more incredible, if you're willing to risk sneaking in.video-player-present
Be warned, however, that it is a very dangerous place to swim. A teenage girl injured her back while jumping from a building into the water in 2014.
Another man's body was found in the quarry just last summer.
Would you dive in if you had the chance?
(via Atlas Obscura)