Scientists have reached Antarctica's largest icebound freshwater lake hidden for millions of years under miles of ice.
A team from Russia's Arctic and Antarctic Research Institute reached Lake Vostok on Sunday after more than two decades of drilling.
The discovery has been avidly anticipated by scientists around the world, who hope that the lake, comparable in area to Lake Ontario, may contain microbial life and provide a clue in the search for life on other planets in similar conditions.
The project has drawn fears that lubricants and antifreeze used in the drilling may contaminate the pristine lake.
Russian researchers have argued that the water from the lake would rush up the borehole driven by a jump in pressure, safely sealing pollutants.