Researchers say Lake Vostok, the largest of Antarctica's buried network of icebound lakes, could reveal new forms of life and show how life evolved before the ice age.
"Yesterday, our scientists stopped drilling at the depth of 3,768 meters [12,362 feet] and reached the surface of the sub-glacial lake," a source with the research team told RIA Novosti Monday.
Some scientists believe the ice cap above the lake has created a seal that has prevented lake water from escaping or anything else from getting inside for the 20 million years the lake has been buried.
Lake Vostok could also offer clues to the possible existence of life in similar extreme conditions on Mars and on Jupiter's moon Europa, researchers said.
Future plans include sending robots down into the lake to study its waters and sediments, they said.