Searching for evidence of hydrothermal activity at Apollinaris Mons, Mars

► We investigate Apollinaris Mons for signs of ancient hydrothermal activity. ► The region shows extensive evidence for volcanic and hydrologic activity. ► We report on various putative signs of magma-water interaction in the area. ► The Apollinaris Mons fan deposits may be thicker than previously estimated. ► Numerous mounds around the volcano could be of exobiological significance.