Scientists discovered a super massive ocean hidden under the Earth's crust.
The water is stored 700 kilometres below the surface of the Earth in a rock known as ringwoodite.
This subterranean reservoir is three times the volume of all the planet's surface oceans combined.
The ringwoodite is like a sponge, soaking up water.
There is something very special about the crystal structure of ringwoodite that allows it to attract hydrogen and trap water.
The high-water storage capacity of minerals in Earth's mantle transition zone (410- to 660-kilometer depth) implies the possibility of a deep H2O reservoir.