Miles beneath Antarctic ice sits a lake cut off from the world for millions of years

Lake Vostok is one of the largest subglacial lakes on Earth, hidden beneath an Antarctic ice sheet more than 3.5 kilometers thick — not discovered until radar surveys in the second half of the 20th century.

Immense ice pressure and geothermal heat from the Earth's interior keep the water liquid despite the extreme cold above, and the lake may have remained cut off from sunlight and the atmosphere for enormous stretches of geological time.

Ice and water samples taken near the lake's boundary have shown traces of microorganisms, but scientists still disagree over how much of that reflects genuine, unique life inside the lake itself versus contamination introduced during drilling.

The lake is often treated as an earthly stand-in for the icy oceans thought to lie beneath the surface of moons like Europa or Enceladus — if something could survive in isolation there, a similar mechanism might be at work elsewhere in the solar system.