This new discovery of a subterranean water deposit, outlined in a new paper in Science, suggests water is indeed underneath the red sands of Mars. Maybe the Red Planet has entire subsurface lake systems like those beneath Antarctica.
www.popularmechanics.com/space/moon-mars/a22541370/underground-lake-liquid-water-mars/
www.theverge.com/2018/7/25/17606966/mars-liquid-water-reservoir-underground-habitable-life-radar
Researchers have found evidence of an existing body of liquid water on Mars. What they believe to be a lake sits beneath the Red Planet’s south polar ice cap, and is about 20km across.
Previous research found possible signs of intermittent liquid water flowing on the martian surface, but this is the first sign of a persistent body of water on the planet in the present day. Lake beds like those explored by Nasa’s Curiosity rover show water was present on the surface of Mars in the past. However, the planet’s climate has since cooled due to its thin atmosphere, leaving most of its water locked up in ice. The discovery was made using Marsis, a radar instrument on board the Mars Express orbiter.
www.bbc.com/news/science-environment-44952710
h/t Diener