It has lain, silent and unseen, buried under miles of ice for 20 million years. Now, after more than two decades of drilling, Russian scientists have reached the pristine surface of a gigantic freshwater lake - Lake Vostok in Antarctica, the Daily Telegraph reported.

The vast depths of Lake Vostok could hold life from the distant past or clues to the search for life on other planets. Scientists have described reaching the lake as "a meeting with the unknown".

Lake Vostok, about 3.8 kilometres (2.4 miles) beneath the surface, is the largest in a web of nearly 400 known subglacial lakes in Antarctica. Researchers believe that microbial life may exist in the dark depths of the lake despite high pressure and constant cold.