Hippalus is an impact crater in southwestern lunar front side between Mare and Mare Humorum Nubium, south of Agatharchides and northwest of Campanus. The crater is largely flooded by lavas of Mare, in the southwestern part of the crater rim is thus completely disappeared.
Through the crater and east of it running in wide, the curvature of the edge of Mare Humorum following sheets, the groove system of Rimae Hippalus. One of the main grooves extends through the center of the crater.
The crater was officially named by the IAU in 1935 after the ancient Greek sailors Hippalus.