Mountains and ice on Pluto. New Horizons view of landscapes of mountains and ice on the dwarf planet Pluto. Great blocks of Pluto's water-ice crust rise up to heights of several kilometres. The mountains end abruptly at the shoreline of the informally named Sputnik Planum, where nitrogen-rich ices form a relatively flat plain. This footage was obtained during the New Horizons flyby of Pluto in July 2015.