In the early 1990s, a Russian drilling rig encountered something strange when boring a hole deep in Antarctica. They had actually found an ancient lake, buried beneath two miles of solid ice!
In the wake of the lake's discovery, there arose considerable debate regarding the likelihood of finding life there. The environment is remarkably similar to the dark and cold ocean below the surface of Jupiter's ice moon Europa, so the discovery of life in Vostok could have interesting extraterrestrial implications. Due to the cold, the complete absence of sunlight, and the toxic levels of oxygen, many scientists are certain that Lake Vostok is sterile. That, however, would be a scientific first, since never before has a completely lifeless body of water been found on Earth. Extremophile organisms have turned up in the unlikeliest of places, including within volcanic vents on the ocean floor, in the rocks deep in the Earth's crust, and in frozen arctic soil.
Link - Thanks Nastia!