Scientists have proven the existence of a rock strata beneath the crust of the earth made of a substance called ringwoodite. The mineral exists largely only at great depths and pressures but it has the interesting characteristic that it can bind and hold lots of hydrogen in the form of water.
Up until now it seems scientists didn't really know where all that water on the Earth's surface came from, the prevailing theory was that it fell to Earth on icy meteorites and such. But the existence of this subsurface water storing rock now suggests that the water actually came from the Earth itself, being released as ringwoodite was raised towards the surface and melted. What is even more interesting is the scientists are saying this layer of ringwoodite could hold up to THREE TIMES the water that is on the surface!
I'm just waiting for some religious theorists to point to this as the mythical source of the waters for the great flood.
New Evidence for an Epic Underground "Ocean" Reservoir