List of plains on the Moon

The Moon has numerous named plains on its surface made of dark-appearing basaltic rocks. The plains are visibly prominent on the near side of the Moon because of their contrasting appearance from the surrounding lunar highlands, which are made up of anorthosite, an igneous rock containing significant concentrations of highly reflective plagioclase feldspar minerals. As with other topographical features on the Moon, the official nomenclature for lunar plains uses a Latin naming system. Due to their darker appearance, differing elevation from the highlands, and visual prominence, noted ancient Greek astronomers such as Plutarch believed the plains were water; subsequent astronomers such as Galileo Galilei and Michael van Langren built on this belief, using Latin words for water bodies in classifying them. The Latin classifications for lunar plains are oceanus (lit. 'ocean'), mare (lit. 'sea'), lacus (lit. 'lake'), palus (lit. 'marsh'), and sinus (lit. 'bay'). The largest plain is Oceanus Procellarum (transl. Ocean of Storms), covering much of the western half of the Moon's near side and the only plain to be classified as an oceanus. Most other prominent plains on the near side are the lunar maria, while the Moon's lacūs, sinūs, and paludes are generally smaller and less visually prominent.

The classification of and other designations for lunar geographic features are determined by the International Astronomical Union (IAU)—the official international organization for the standardization of astronomy.