700 km deep ocean found beneath Earth's surface at Northwestern University, challenging origin theories of Earth's water.

Scientists at Northwestern University discovered a hidden ocean, 700 km beneath Earth's surface, within a mineral called ringwoodite. This subterranean ocean, three times the size of all surface oceans combined, challenges existing theories about the origin of Earth's water. Previously, scientists believed water originated from comet impacts, but the discovery suggests Earth's oceans might have emerged from deep within the Earth itself.