Scientists have discovered a massive 'ocean' beneath Earth's surface bigger than all the seas above land

Nearly three quarters of the Earth is covered in water, and it turns out there're more below the planet's surface too.

That's because scientists have discovered a reservoir of water hidden beneath our feet that is equal to three times bigger than the oceans that sit on the surface.

Pixabay

This huge supply of water is buried a whopping 400 miles underground - so it's not exactly accessible - and was discovered by scientists nearly a decade ago in 2014. It's contained inside a blue rock known as 'ringwoodite' in the Earth's mantel, which acts as a sort of sponge. So it's not a liquid, solid, or gas, but a fourth molecular structure of water contained inside the mantle rock.

Geophysicist Steve Jacobsen, who was part of the monumental discover, explained how it works: "The ringwoodite is like a sponge, soaking up water, there is something very special about the crystal structure of ringwoodite that allows it to attract hydrogen and trap water. This mineral can contain a lot of water under conditions of the deep mantle."

Pixabay

The discovery of the water was by scientists from Northwestern University in Illinois using seismometers to measure the waves being generated by earthquakes across the USA. The research found that waves weren't limited to the Earth's surface, but instead moving throughout the planet's core. During the study, scientists researched the speed and depth of those waves, before being able to determine what sort of rocks the water was being contained in. The study found the rocks were ringwoodlite, due to it containing up to 1.5 percent water.

If the ringwoodite under the surface has just 1 percent water in its molecular build-up, it would mean that it holds three times more water than all of the oceans on the Earth's surface. For now, researchers have only found evidence of the ringwoodite rock beneath the surface of the US.

Jacobsen and his team want to determine whether or not this layer wraps around the entire planet Earth.

Pexels

This discovery isn't just about finding more water, but instead could be crucial for understanding how Earth was formed. It also adds further evidence to the theory that the Earth's water 'came from within', rather than from asteroids and comets.

Jacobsen explained at the time: "I think we are finally seeing evidence for a whole-Earth water cycle, which may help explain the vast amount of liquid water on the surface of our habitable planet.

"Scientists have been looking for this missing deep water for decades."