The world's oldest water, which is locked deep within the Earth's crust, is present at a far greater volume than was thought, scientists report.
The liquid, some of which is billions of years old, is found many kilometres beneath the ground.
Researchers estimate there is about 11m cubic kilometres (2.5m cu miles) of it - more water than all the world's rivers, swamps and lakes put together.
The study was presented at the American Geophysical Union Fall Meeting.
It has also been published in the journal Nature.
The team found that the water was reacting with the rock to release hydrogen: a potential food source.
It means that great swathes of the deep crust could be harbouring life.To read more, click here.