It's a hidden world that hasn't seen the light of day for 20 million years.
Russian scientists are on the brink of drilling into a lake in the Antarctic which is buried more than two miles underneath ice.
Last year the scientists working in freezing temperatures at Lake Vostok came within ten to 50 metres of the surface of the 'relic lake'.
The scientists are hoping to learn more about what life-forms existed 20 million years ago.
But with the summer almost over, the team will have to leave the remote site within days - before it gets too cold for a plane to land.
If they do not manage to drill through, they will not be able to return until December.
However, when the breakthrough moment comes they must take care not to contaminate the hidden underground world with bacteria and fluids from the drilling. Read More