Beneath the East Antarctic ice lies a lake the size of Lake Ontario, sealed from the sky for millions of years. Here is what is down there, and how we know.
Vostok Station sits high on the East Antarctic plateau. On 21 July 1983 its thermometer read −89.2°C — still the lowest natural temperature ever recorded.
The lake runs roughly 250 km long and 50 km across at its widest, covering about 12,500 sq km. Estimates put its volume near 5,400 cubic kilometres of water.
Nothing marks it on the snow. Airborne radar and satellite altimetry gave it away — a suspiciously flat patch where the ice sheet floats on hidden water.
The ice overhead is close to 4,000 m thick — roughly twelve Eiffel Towers stacked end to end between your boots and the first drop of liquid water.
Two forces keep it liquid near −3°C. The weight of the ice pushes water's freezing point down, and heat seeping from the rock below warms it from beneath.
At the ice-water boundary the pressure reaches about 345 bar — close to 5,000 psi, comparable to the crush roughly 3.5 km down in the open sea.
All that pressure forces gas into solution. Estimates suggest oxygen and nitrogen levels around 50 times those of an ordinary freshwater lake at the surface.
Best estimates put its isolation at 15 to 25 million years. Whatever lives down there has not met sunlight since long before our species walked the planet.
After two decades of stop-start drilling a Russian team hit water at 3,769 m on 5 February 2012. It surged up the borehole and froze there as a solid plug.
Studies of that plug reported thousands of microbial gene sequences, though drilling fluid keeps them contested. Europa hides the same setup — ice over water.