And no, we're not talking about an underground sea with waves, fish, and a shoreline.

Something much stranger is happening deep beneath our feet.

Far below Earth's surface, scientists have discovered evidence that enormous amounts of water may be locked inside a mineral called ringwoodite.

Ringwoodite exists deep within Earth's mantle, roughly 410 to 660 kilometers beneath the surface.

And here's the strange part:

The water isn't necessarily sitting there as a liquid ocean.

It's locked into the crystal structure of the rock itself.

Think of it less like a giant underground swimming pool...

and more like an enormous sponge made of minerals, storing water inside its atomic structure.

Scientists became particularly interested in this because laboratory experiments showed that ringwoodite can cont ...