The Rummu quarry is a submerged limestone quarry located in Rummu, Vasalemma Parish, Estonia. Much of the natural area of the quarry is under a lake formed by groundwater, and is situated next to a spoil tip. The quarry is close to two former prisons, the nearest being the former Rummu prison.
The quarry was formed in the late 1930s for open mining of limestone and Vasalemma marble. The latter is a specific kind of limestone with its structure and texture resembling that of marble. Excavation was performed as hard labour by Murru and Rummu prisoners. The inmates excavated and processed limestone from the water-drained quarry until 1990s, when pumping of water ceased, and the quarry quickly filled with groundwater, immersing in it some of the utility buildings and machinery, thus forming a lake. Next to the lake is the Vasalemma spoil tip (slag heap). Over time, the spoil tip got its unique appearance through erosion by water.
The Rummu open-air prison was merged with the Murru prison in the 1990s, which itself was closed on 31 December 2012.
The Rummu quarry had become a featured location for nature photography, hiking, rafting, scuba diving, as a summer spot, musical and sports events, and as a filming location for its unique layout. The site was depicted in the post-apocalyptic short film The Most Beautiful Day (by Einar Kuusk), and in the video for Alan Walker's hit song "Faded".
Jump-diving into the lake off derelict buildings is very dangerous, and professional divers have made public recommendations against this practice, because the lake bed contains pieces of thick concrete, tree branches, spikes of rebars, metal construction (including machinery), and plenty of barbed wire.
On 7 August 2014, a 17-year-old girl injured her back when jumping into the water off a derelict building.
Late in the day of 21 July 2016, a 35-year-old man was found drowned in the quarry.
The territory is private property, and belongs to KB Auto Eesti OÜ, the CEO of which is Gunnar Bergvald, a former prison official.