@rosborne979,
The hydrological flow patterns which can be seen on the surface of Mars would as well have been created by glaciers as by liquid water. There are two camps on the "wet Mars" hypotheses, one that there was a long period of surface water and a dense atmosphere, the other that there was only a short period. There are many planetologists who will point out that there is no unambiguous evidence that there was liquid water on the surface. It is, however, a majority opinion that there once was. However, that was likely to have been three and a half or even four billion years ago. The "Big Hit" hypothesis--that a planetesimal collided with the northern hemisphere of Mars about three and half billion years ago accounts for it no longer having a dense atmosphere and for the huge discrepancy in the elevation of the northern and southern hemispheres. The "chaoses" of the southern hemisphere are from 10,000 to 20,000 feet higher in elevation than the northern hemisphere above 30 degrees of latitude north.
Mars has not had an active volcanic cycle for millions of years, so the idea of life surviving or arising in volcanic vents is dubious. But the core of Mars is still hot, and i agree that if life is found, it will likely be underground. Underground environments would also provide protection from solar radiation, which right now would kill you in a few years if you weren't able to get underground for long periods of time. There may well be a good deal of permafrost, and at certain depths that could be liquid due to the pressure of the regolith above it.
Schiaparelli, who named the most prominent albedo features on Mars, saw what he considered evidence of hydrological flow. This has been confirmed, but is not necessarily evidence of liquid water--glaciers can make the same channels, it just takes them longer. Schiaparelli named them channels, which in Italian is
canali, so that's how we got all that old "canals on Mars" BS. Thanks to journalists, of course, who wouldn't know science if it bit them in the ass.