Which lake is the largest subglacial lake known on Earth?

Lake Vostok is the largest known subglacial lake on Earth.

It lies beneath the central East Antarctic Ice Sheet, near Russia’s Vostok Station, buried under roughly 3.5 kilometres of ice. Radar and satellite studies place it at about 250 kilometres long and up to 50 kilometres wide, with an estimated area of approximately 12,500 square kilometres. Pressure from the overlying ice helps keep its water liquid despite the extreme cold.

The lake’s existence was first suggested by Soviet seismic surveys in the 1950s and 1960s. British and Russian research later confirmed it, with satellite laser-altimetry evidence published in the 1990s. Scientists are especially interested in its isolated environment, because the water may have been separated from the surface for millions of years and could contain unusual microbial ecosystems.

Russian drilling reached the lake in February 2012, but contamination concerns have complicated direct sampling. Lake Ellsworth, Lake Mercer, and Lake Whillans are also important Antarctic subglacial lakes, but none is as large as Vostok.