The underground ocean that produced some of the stunning features on Pluto's surface may still be splashing around beneath the crust today.

If Pluto's subsurface ocean had frozen over completely, it would have formed highly pressurized ice that would have caused the dwarf planet to shrink, according to new research. The canyons and valleys on Pluto seem to have formed as the dwarf planet swelled up, rather than as it shrank, indicating that a liquid ocean most likely sits beneath the thick ice crust today, researchers said in the study.

http://www.michellhilton.com/2016/06/plutao-pode-abrigar-um-oceano-liquido.html