One Giant Sponge Ball.

“The work also adds credence to the idea that the earth’s water accumulated in the interior during the planet’s formation, rather than arriving later through the bombardment of icy comets. In this view, water bound up in minerals in the mantle, the 1,800-mile-thick layer between the thin crust and the hot metallic core, degassed over time and reached the surface.”

A follow-up to this post: Henry Fountain explains further the recent evidence suggesting vast water deposits, deep below the surface of the planet. “The water is not liquid, but rather bound in minerals that exist at the extreme pressures found at such depths.”