https://www.cnet.com/news/liquid-lake-spotted-on-mars-express-south-pole-but-its-hidden/

Mars may look dusty, dead and dry, but now scientists have discovered strong evidence of a lake of liquid water hidden beneath the Red Planet's southern ice cap. 

For centuries there have been hints and hopeful speculation of a wetter side of Mars, from alien-built canals to some dark streaks that kinda sorta look like damp sand. But time and again, further investigation always seems to reveal any water spotted on our neighbor world is either an illusion or frozen stiff.