There is liquid…

There is liquid water on Mars. The watery area in question is about 20 kilometers in diameter, and while depth can’t be determined, the deposit would likely have to be at least a meter thick to produce the reflection observed. So at a bare minimum we’re probably looking at a serious quantity of water, on the order of millions of liters.
“It’s not anything you’d want to swim in — negative 80 degrees Fahrenheit, or negative 60 Celsius, and probably more of a thick sludge subsiding here and there into “brine pools.” If I’m not mistaken you’d probably also be crushed like a bug if you weren’t inside some kind of pressure vessel. Still — it’s liquid water. On Mars. Today.”