Scientists from Northwestern University and the University of New Mexico have discovered evidence of a vast underground reservoir with three times the volume of all the oceans combined.

The water is locked in a mineral called ringwoodite and located in a layer of hot rock 400 miles beneath the Earth's surface. Researchers believe the hidden water could be the source of the Earth's oceans, and contradict prevailing theories about how water arrived on Earth.

The new evidence, published last week in the journal Science, could change what we know about the composition of the Earth and how the planet evolved.

Geophysicist Steve Jacobsen, one of the co-authors of the study, joins Take Two to explain the findings of the study.