Scientists Detect Possible Hidden Ocean Deep Beneath Mars' Surface

Seismic data suggests that Mars may harbor a vast hidden ocean of liquid water far beneath its surface.

A study published on April 25 in the National Science Review reveals that seismic wave recordings from deep within the Red Planet indicate a potential layer of liquid water residing in Martian rock, located roughly 3.4 to 5 miles (5.4 to 8 kilometers) below the surface.

Researchers estimate that the total volume of this hidden water could cover the entire Martian surface with an ocean 1,700 to 2,560 feet (520 to 780 meters) deep—comparable to the amount of liquid water stored in Antarctica’s ice sheet.

Mars, our planetary neighbor, is believed to have once been rich in water. Between 4.1 and 3 billion years ago, it likely had extensive water systems, including valley networks, deltas, and sedimentary rock layers—evidence of long-term liquid water flow.

However, over time, Mars lost its magnetic field, exposing its atmosphere to solar radiation, which gradually stripped it away. As the atmosphere thinned, surface temperatures plummeted. Scientists explain that the planet’s liquid water either escaped into space, froze beneath the surface or at the poles, or became chemically bound within hydrated minerals in the crust.