汽海（拉丁语：Mare Vaporum）是月球一座位于澄海西南侧和雨海东南侧之间的月海。该月海周围地区地层形成于早雨海世时期，月海自身地层则形成于爱拉托逊纪。它坐落在风暴洋内一个古老的盆地或撞击坑中，直径245公里(152英里)，面积约5.5万平方公里(2.1万平方英里)，大约形成于45.5亿年-38.8亿年前的早雨海世期。月海南面一条浅色细线是许癸努斯月溪(Rima Hyginus)，西北与亚平宁山脉相接壤。该月海名称为1651年意大利天文学家乔万尼·巴蒂斯塔·里乔利(Giovanni Battista Riccioli)所命名。

Mare Vaporum (the "sea of vapors") is a lunar mare located between the southwest rim of Mare Serenitatis and the southeast rim of Mare Imbrium. The lunar material surrounding the mare is from the Lower Imbrian epoch, and the mare material is from the Eratosthenian epoch. The mare lies in an old basin or crater that is within the Procellarum basin. The mare is 245 kilometers (152 mi) in diameter and 55,000 km (21,000 sq mi) in area. It may be from the Pre-Imbrian period, which lasted from 4.55 to 3.85 billion years ago. To the south of the mare is a light colored thin line. This feature is Rima Hyginus. The mare is bordered by the mountain range Montes Apenninus. The mare was named by Giovanni Battista Riccioli in 1651.