Vostok, Lake (väˈstôk) [key], c.3,900 sq mi (10,000 sq km), c.155 mi (250 km) long and 30 mi (50 km) at its greatest width, in East Antartica beneath the remote Vostok research station. One of the largest subglacial lakes in Antarctica, the presumably freshwater lake is located beneath c.2.5 mi (4 km) of ice, and is 30 to 1,650 ft (10–500 m) deep. It is divided into north and south basins, which are separated by an underwater ridge. Since the lake was discovered in 1996, scientists have speculated it may hold microbes that have been isolated for millions of years, but have not drilled down to its waters for fear of contaminating them. Cores drilled to within c.500 ft (150 m) of the lake have returned ice samples some 420,000 years old; drilling reached the lake's surface in 2012.