
Mars hints at a long-lived ocean through a vast ancient coastline
New analysis of Martian topography identifies a broad, flat coastal shelf in the planet’s northern hemisphere that would have sat roughly 1,800–3,800 meters below ancient sea level, suggesting a global ocean may have covered about a third of Mars for millions of years; accompanying delta patterns align with shorelines, making a long-lived ocean a plausible part of Mars’ past and guiding where sedimentary evidence of life might be found by future missions.

