Models interiors of icy ocean worlds based on geophysical constraints. Considers seawater, water, MgSO4 (aq) and NH3 (aq) oceans; ices I, II, III, V, VI; rock mineralogies of chondrite and pyrite; metallic cores of gamma-iron and FeS rich iron including melts. Includes applications to Europa, Ganymede, Callisto, Enceladus, Titan.