Dellah was an M-type (Earth-like) planet orbiting a single star. It had no moons. It had temperate seas of roughly the same composition as those on Earth. (PROSE: Ship of Fools) Dellah was mostly covered by temperate oceans and dotted with islands. Its largest body of water, the Silvasic Sea, took up most of the temperate zone (between 23.5°S and 66.5°S) in Dellah's southern hemisphere. (PROSE: Dry Pilgrimage) A day on Dellah was 26 hours long. (PROSE: Mean Streets)