By studying seismic waves, researchers have found a layer deep beneath the surface of Mars that could contain enough liquid water to flood the planet with an ocean thousands of feet deep.

Liquid water once shaped the Martian landscape dramatically, carving valleys, filling lakes, and forming vast oceans. Billions of years ago, during Mars' early days known as the Noachian and Hesperian periods,

It is noted that seismic wave recordings indicate that a layer of liquid water may be hidden at a depth of 5.4 to 8 km below the surface. Scientists estimate that the total volume of water under the planet’s surface could flood Mars, forming an ocean 520 to 780 meters deep.

Scientists using data from Nasa’s InSight lander find mysterious zone they say is best explained by a layer of water-saturated rock.

Chinese and Australian boffins ask what else could be slowing down seismic waves as they pass through the Red Planet? Mars may still be home to oceanic quantities of liquid water, according to a recent paper published by the National Science Review.