You’ve probably seen several abandoned theme parks, but what about a prison? Off the coast of Estonia, there’s a strange abandoned jail known as the Murru prison complex where convicts used to mine limestone in the quarry next door. However, the quarry filled with water, and soon the prison itself also drowned in what locals call “the blue lagoon.” Now paddleboarders, kayakers, scuba divers and many Instagrammers spend their days at the sunken jail, which may look like an under and above-water playground at first glance. Continue reading for a night dive video and more information.

According to Vornaskotti, “The location is a quarry that is now full of water. One side of the quarry used to have some heavy machinery that was left on the bottom, but they have been raised, so there’s very little to see there nowadays. On the other side of the quarry there’s at least one totally submerged building, and another ruin jutting up from the water.”