Mare Insularum (the "sea of islands") is a
lunar mare located in the Insularum basin just south of
Mare Imbrium. The basin material is of the
Lower Imbrian[?] epoch, with the mare material of the
Upper Imbrian[?] epoch. The mare is bordered by the
craters Copernicus[?] on the east, and
Kelper[?] on the west.
Oceanus Procellarum joins the mare to the southwest.
Copernicus is one of the most noticeable craters on the Moon. The rays from both Kepler and Copernicus protrude into the mare. It is located near Fra Mauro.