Mare Insularum is a lunar mare located in the Insularum basin just south of the western Mare Imbrium. The basin material is of the Lower Imbrian epoch, with the mare material of the Upper Imbrian epoc
Mare Insularum, bordered by the craters Copernicus on the east, and Kepler on the west. Oceanus Procellarum joins the mare to the southwest. The northern edge of Mare Cognitum is visible at the bottom of the photo, and Fra Mauro is the grey patch in the lower right.