Jules Verne wins this round. The center of the Earth may hold a reservoir of water as large as all the planet's oceans combined, according to new research published in the journal Nature. Scientists say they found a rare mineral called ringwoodite that indicates vast quantities of water exists some 250 to 375 miles under the surface. The below-the-surface resource would be locked in molecular form in certain types of rocks, they theorize. Researchers only first discovered evidence of ringwoodite in 2008, when it was found inside a brown diamond dug up by treasure hunters.