NASA/JHUAPL/SwRIThese mountains aren't static and stable, but rather are temporary water-ice mountains atop a volatile, nitrogen sea. NASA/JHUAPL/SwRIThe mountains only appear between the hilly highlands, after the edge of a basin rim, and young plains with flowing canals. NASA/JHUAPL/SwRIThese young plains occur in Pluto's heart-shaped lobe, which itself was caused by an enormous impact crater. James T. KeaneOnly a subsurface, liquid water ocean beneath the crust could cause the uplift we then see, leaving the nitrogen to fill it in. NASA/JHUAPL/SwRIThe observed gravitational anomaly under Sputnik Planitia further indicates a sub-surface ocean.

Source: Forbes February 19, 2018 15:21 UTC