But Russia must wait for the Antarctic summer to collect and study water samples, leaving the door open for U.S. and British missions to explore two other subglacial lakes and beat it to be the first to answer the question of whether life exists under the polar ice.
"We call it extraterrestrial life," Russian astrobiologist Sergei Bulat told Vesti 24 state television. "It will be useful to the search for life on other icy planets like Jupiter's satellite Europa."
A century after the first expeditions to the South Pole, the discovery of Antarctica's hidden network of subglacial lakes via satellite imagery in the late 1990s set off a new exploratory fervour among scientists the world over.
"This is scientific exploration, this is work that no one has ever done before," Martin Siegert, head of the University of Edinburgh's School of Geosciences, told Reuters.
"This is probably one of the last frontiers on our planet that remains largely unknown to us," said Siegert, who is leading a British expedition to explore Lake Ellsworth in West Antarctica in 2012-2013.
Experts say the ice sheet acts like a blanket, trapping in the Earth's geothermal heat and preventing Antarctic lakes from freezing.
If there is life in Vostok and other ice-bound lakes, it is unlikely to be anything more complicated than single-cell organisms adapted to survive in the high-pressure, sunless environment, Siegert said.
"It is just imagination, we don't really know until we go in," he said.