A vast reservoir reshapes our understanding today.

For years geophysicists suspected that Earth held more water locked deep within its interior than the surface oceans ever revealed. Now new evidence confirms that a massive reservoir sits hundreds of miles down in the transition zone between the upper and lower mantle. It does not look like the oceans we know, yet it may hold as much water as all of them combined. The discovery challenges how our planet formed, how it cycles water and how fragile the surface environment truly is.



