Scientists have discovered a sixth ocean, three times larger than all surface oceans combined and approximately 700 kilometres beneath the Earth's surface.

• Scientists at Northwestern University revealed that the ocean exists in the Earth's mantle.
• The pool of water was found to be trapped within a blue rock formation known as ringwoodite.
• The discovery supports the theory that oceans originated from Earth’s interior rather than from cometary impacts.
• This helps to further explain the consistent size of our surface oceans over millions of years.