Lake Vostok contour map. Lake Vostok, lying beneath several kilometres of ice, is the largest known subglacial lake in Antarctica. It has a surface area of around 14,000 square kilometres, a volume of around 5400 cubic kilometres, and a depth of 400-800 metres. This contour data was obtained by gravity measurements, and shows two separate basins (blue), separated by a large ridge. The colour-coding is explained by the key at right. The other axes show latitude and longitude. Points are marked on the A-A' and B-B' lines. It takes between 55,000 and 110,000 years for water to cycle through the lake. This map was published in 2004.