The key word here is 'in' the Earth – or underground. At http://archaeologynewsnetwork.blogspot.co.uk/2014/03/rare-mineral-points… … which came about after the discovery of a water rich gem stone. The rough brown diamond has been naturally sculptured to its unusual shape by corrosive mantle fluids during transport to the surface – or that is what is envisaged. The mineral is known as ringwoodite and was found in Brazil. Analysis shows it is composed a significant amount of water, a finding that is said to confirm theories of vast volumes of water trapped beneath the surface of the Earth, between the Upper and the Lower Mantle regionbs – see Nature March 13th 2014. It is hypothesized there is as much water underground as there is on the surface – including all the oceans.