Notes from an underground lake © Konstantin Trubavin/Offset by Shutterstock
The Ruskeala Mountain Park is an eerily beautiful reminder of the booming mining industry that thrived for centuries in this area of Russia near the border with Finland. Located on the site of an abandoned marble quarry, the park opened to the public in 2005. The centuries-old quarry has been flooded with groundwater since the end of World War II, although some old buildings and kilns from the mines are still intact.