From the elusive plumes of Europa to Enceladus’ dramatic cryovolcanic geysers and the extreme volcanism of Io, the Solar System hosts a wide spectrum of active geological processes. Over the past decade, major breakthroughs in planetary geophysics have been made by spacecraft missions, space-based telescopes, and ground-based observatories including Keck. In this talk, I will survey recent discoveries on the nature of geological activity on Solar System satellites, and will discuss new mysteries that these discoveries have uncovered.