Water covers around 70 percent of the Earth surface, but a vast amount also lies inside our planet. In the first study, researchers from Florida State University and the University of Edinburgh estimated that water exists far deeper in the Earth than previously thought, stored in a mineral called brucite. Although the amount of water is unknown, researchers believe it could account for as much as 1.5 percent of the weight of the planet – the same amount of water as all the world’s oceans put together.

An ocean of water is found 620 miles below Earth’s surface – Daily Mail