静海(拉丁文"Mare Tranquillitatis"-意为"安宁之海"或"安静之海")是一座坐落在月球静海盆地内的月海。

该月海的地层由形成于晚雨海纪青年期中间的玄武岩所构成。四周的山脉被认为是形成于早雨海纪代，但盆地实际可能属前酒海纪。静海盆地边缘不规则，缺少明确的多环状结构。静海、酒海、危海、丰富海及带有风暴洋二个贯通环的澄海交错构成了盆地内外不规则的地形。位于月海西北边缘上的睡沼，表面填满了从静海漫溢出的玄武岩。

相较于月球其它部分，静海呈现出一种淡蓝色，当从多张照片中提取和进行色彩处理时，该色彩非常突出，这很可能是其玄武石土壤或岩石的金属含量更高的缘故。

Mare Tranquillitatis (Latin for Sea of Tranquility or Sea of Tranquillity (see spelling differences)) is a lunar mare that sits within the Tranquillitatis basin on the Moon. The mare material within the basin consists of basalt formed in the intermediate to young age group of the Upper Imbrian epoch. The surrounding mountains are thought to be of the Lower Imbrian epoch, but the actual basin is probably Pre-Nectarian. The basin has irregular margins and lacks a defined multiple-ringed structure. The irregular topography in and near this basin results from the intersection of the Tranquillitatis, Nectaris, Crisium, Fecunditatis, and Serenitatis basins with two throughgoing rings of the Procellarum basin. Palus Somni, on the northeastern rim of the mare, is filled with the basalt that spilled over from Tranquillitatis.