Mare Undarum (Moon)

"Sea of Waves"

Mare Undarum is an uneven lunar mare located just north of Mare Spumans on the lunar near side,. The surrounding basin material is of the Nectarian epoch, with the mare basalt being of the Upper Imbrian epoch. The crater Dubyago can be seen on the southern edge of the mare. (wikipedia entry)

A mare is a "sea" or large circular plain. On the Moon they are named after latin terms describing weather and other abstract concepts.