Presented at the Global Ocean Salinity and the Water Cycle WorkshopConceived in the late 1990s, and proposed to NASA's Earth System Science Pathfinder (ESSP) Missions program in 2001-2002, the Aquarius mission was selected to resolve missing physical processes that link the water cycle, the climate, and the ocean by measuring sea surface salinity (SSS). The satellite was developed in partnership with Argentina as the joint Aquarius/SACD mission, and included complementary sensors provided by Argentina, Italy, France and Canada.The primary salinity sensor, Aquarius, provided global coverage every 7 days at 150 km spatial resolution for at least three years to resolve the global mean, seasonal and interannual variability. While the scientific focus was basin-scale, the capability to resolve smaller scale features exceeded expectations; such as tropical instability waves, river plumes and ocean fronts. Other key science achievements include improving tropical Pacific SST forecast skill, linking SSS changes to terrestrial rainfall, estimating total alkalinity, and discovering the range of temporal variability of the SSS field. Various examples will be presented.