A former Soviet prison in Estonia has now become a diving attraction. Established in the 1940s, it was used as a quarry for Vasalemma marble with prisoner labour. When Estonia became independent, the labour prison in Rummu fell and a quarry was closed. Thus natural ground water flooded the quarry and the prison so fast that all the machinery and buildings ended up underwater. Now this place looks like a blue lagoon.
The Rummu underwater prison is a very popular tourist destination and diving spot. Locals usually come here to swim in summer. The water is clearer in autumn, so it's best to dive here at this time. There is one thing you should know that it is an unofficial and unguarded place for swimming or diving. Diving can be dangerous if you don't know what is waiting for you. Guided tours can be a safer option.