The Lost World of Lake Vostok

In 1957 the Russians established a remote base in Antarctica -- the Vostok station. It soon became a byword for hardship -- dependent on an epic annual 1000km tractor journey from the coast for its supplies. The coldest temperature ever found on Earth (-89°C) was recorded here on the 21st July 1983. It's an unlikely setting for a lake of liquid water. But in the 1970's a British team used airborne radar to see beneath the ice, mapping the mountainous land buried by the Antarctic ice sheet. Flying near the Vostok base their radar trace suddenly went flat. They guessed that the flat trace could only be from water. It was the first evidence that the ice could be hiding a great secret.

http://www.bbc.co.uk/bbctwo/