Ancient Beaches Found on Mars Reveal The Red Planet Once Had Oceans

25 February 2025
By MICHELLE STARR





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An artist's impression of an ocean on Mars. (ESO/M. Kornmesser)

Mars – dusty, dry, and desert-clad – was once so rich in water it had not just lakes, but oceans, according to a new study.

Observations using ground-penetrating radar have revealed underground features consistent with beaches on the red planet, 4 billion years ago. It's some of the best evidence to date that Mars was once so soggy as to host a northern sea. The research team has named that sea Deuteronilus.

"We're finding places on Mars that used to look like ancient beaches and ancient river deltas," says geologist Benjamin Cardenas of The Pennsylvania State University. "We found evidence for wind, waves, no shortage of sand – a proper, vacation-style beach."

The water history of Mars is a huge puzzle. At a glance, the planet looks as though it has never seen a drop of liquid. Its global dust storms are legendary.

It would be easy to believe that Mars has always been a ball of dry rock; yet a growing, and overwhelming, body of evidence shows that Mars didn't just have liquid water on its surface once upon a time, but that the liquid flowed in abundance.