Recent advances in spacecraft explorations have revealed the presence of liquid water on multiple Solar System bodies, including Mars, icy satellites, and volatile-rich dwarf planets. To further understand the formation, evolution, and habitability of these “aquaplanets” in the Solar System, knowledge of physico-chemical processes that characterize aqueous environments becomes critical. These processes include water-rock reactions, photochemistry, hydrological and geochemical cycles, and degassing from the interiors. These processes generate both oxidants and reductants and transport them in hydrospheres, creating bioavailable chemical disequilibria. This session covers topics relevant to these physico-chemical processes on aquaplanets (including Earth), e.g., geochemical processes on terrestrial planets, planetary hydrology and climates, and interior evolutions. This session also welcomes observational studies of geochemical signatures of aqueous environments on Solar System bodies using spacecrafts, rovers, and telescopes.