Of course there are nice sunny warm spots that get well over 0 C. There are some nice places to put a deck chair and sip lemonade in the sun at +20 C, if you don't mind the atmosphere not being there.

But think carefully what bits get warm.

On Earth, the hot sand of a desert or a beach is underlain at only a few cm by cool sand from the night before. Anything more than a few cm down sees diurnal (daily) average temperature, not local instantaneous temperatures.

Anything a metre down sees annual average temperature and wouldn't melt if you let off an atomic bomb airbust above it.

One of the paradoxes of Mars is that the warmest areas are the driest areas. This is because water is a good thermal buffer (as is ice, and cold ice also conducts heat well and stops the surface warming up). On Earth, the areas that get hottest are also the driest. We call them deserts.

Look also at your domestic freezer for clues to how water and ice behave on Mars.

If you find an old purchase in the bottom of your freezer and the plastic wrap is torn - look how tough and dry the meat is. It's been freeze dried. At the same time, ice gathers on the cold walls of the freezer. - ice migrates from solid to solid form, via vapour phase, without ever being liquid. And it concentrates in the coldest places. In your freezer, that's the cooling unit - the wires, pipes, and walls. On mars, it's the polecaps and sheltered areas inside craters at high latitudes.

That's where the surface ice is on Mars. And there's subsurface permafrost, but it's frozen to a depth of 5-20 km.

OK, so that's what Mars is like.

Now, how do you get a whole flood of water to burst out from under the ground?

Or how do you get to melt a large ice body at the surface?

It isn't easy. There are ways to do it but they are very borderline for surface water. If you understand the physics properly, then you can perhaps discuss which areas and times liquid water is possible, but be aware that the surface of Mars is covered in fine rock dust with puverised minerals in it like Olivine that would rot down to clay if they had ever been wet. There is almost no clay on Mars. There is abundant clay on Earth. That's a message about water availability.

Now go find an "innocuous" brine on Mars...