There's a lake that's a 'dead sea'... but not because of salt! - Apparently.
Lake Vostok, located in Antarctica, is a subglacial lake, meaning it's trapped beneath a thick layer of ice. Despite being surrounded by water, the lake itself is a "dead sea" because of its extreme environment, with pressures reaching 400 times that of the atmosphere. The lake is thought to have remained undisturbed for over 14 million years, with some estimates suggesting that it may have been isolated since the time of the dinosaurs.