Exploratour - Water on Mars
Mars Cryosphere
The drawing shows the Martian surface, and the unusual changes in height. You can see the depths to which the ground may be frozen at various latitudes of Mars.
The ground is less frozen at the lower latitudes (near the equator) because it is warmer near the equator and water can evaporate. The frozen ground may be only 2.5 km deep at the Martian equator while it may be 6 km deep at the south pole.