hi, i would like to ask a question... should water doesnt exist in mars surface cause the gravity is to low to sustain it in liquid form on surface, but maybe, in around the mantle?

cause i thought about the gravity on mars and on earth, and we have this oceans cause the gravity sustain it in some how right? The proximity to the sun, the habitable zone... 

otherwise, could mars gravity be low to sustain water in liquid form, on surface?

Comment deleted

We have water because of air pressure and temperature mars has little to no air pressure so it's extremely cold