Mare Serenitatis sits just to the east of Mare Imbrium .
it is located within the Serenitatis basin, which is of the
Nectarian epoch. The material surrounding the mare
is of the Lower Imbrian epoch, while themare material
is of the Upper Imbrian epoch. The mare basalt covers
a majority of the basin and overflows into Lacus
Somniorum to the northeast. The most noticeable
feature is the crater Posidonius on the northeast rim
of the mare. The ring feature to the west of the mare
is indistinct, except for Montes Haemus, The Serenitatis
connects with Mare Tranquillitatis to the southeast.