Lake Vostok is in Russia; a sub-glacial lake in Antarctica. It is the largest of about 400 of such lakes in that continent. It is located at the south pole, about 4000m beneath the surface of the ice. Lake Vostok is an age-long (15 million years) sealed body of water containing various organisms.
Vostok Station, a research station, sits above the lake.
“The presence of a large buried lake was first suggested in the 1960s by a Russian geographer/pilot who noticed the large, smooth patch of ice above the lake from the air. Airborne radar experiments by British and Russian researchers in 1996 confirmed the discovery of the unusual lake.”