Pluto

Science Daily: New analysis adds support for a subsurface ocean on Pluto - Findings suggest other large objects in the Kuiper belt may also have liquid oceans beneath frozen shells

summary - A liquid ocean lying deep beneath Pluto's frozen surface is the best explanation for features revealed by NASA's New Horizons spacecraft, according to a new analysis. The idea that Pluto has a subsurface ocean is not new, but the study provides the most detailed investigation yet of its likely role in the evolution of key features such as the vast, low-lying plain known as Sputnik Planitia (formerly Sputnik Planum).