The total amount of groundwater on our planet, held in rock and soil below our feet, is estimated to be 23 million cubic kilometers 12. This vast underground reservoir contains three times as much water as all of Earth’s oceans combined!

While we often think of the oceans as the primary source of Earth’s water, it turns out that most of our planet’s water may actually be locked away deep underground. This hidden water resides in a layer known as the transition zone, approximately 400 miles (700 kilometers) below the Earth’s surface. Here’s how it was discovered:
Ringwoodite: Scientists found evidence of water in a mineral called ringwoodite, which is chemically similar to peridot (a green gemstone). Ringwoodite had previously been found only in meteorites and was discovered in a diamond ejected from a volcano in 2008. The ringwoodite samples came from the transition zone between the upper and lower mantle.
Seismic Waves: Researchers monitored seismic waves generated by earthquakes. These waves change velocity depending on the material they pass through. By measuring these changes, geologists mapped what lies beneath the Earth’s surface. They detected signs of wet ringwoodite in the transition zone, where the intense heat and pressure cause the trapped water to be squeezed out. Imagine rock “sweating” water along its grain boundaries!
Mind-Boggling Amount: If all the ringwoodite in the transition zone is as damp as the samples detected, it would hold three times as much water as all of Earth’s oceans combined. This discovery significantly alters our understanding of where Earth’s water comes from and how it has been present throughout our planet’s history.
So next time you gaze at the blue expanse of the oceans, remember that there’s an even greater reservoir of water hidden beneath our feet, deep within the Earth’s rocky embrace.



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It most likely meant the water is not free down there to flow, its chemically combined like stone. to minerals etc. ____________________________________