Mare Ingenii ("sea of cleverness") is one of the few lunar mare features on the far side of the Moon. The mare sits in the Ingenii basin. This basin material is of the Pre-Nectarian epoch. The mare material located in Ingenii and the surrounding craters is of the Upper Imbrian epoch. The dark circular feature which dominates this mare is the crater Thomson (112 km diameter), with the overflow from Ingenii/Thomson directly to the east. Mare Ingenii is incompletely and thinly covered over much of its expanse with mare lava sheets. The best flooding occurs in the crater Thomson in the ENE part of the Mare Ingenii basin. The light grey crater to the south of Ingenii is Obruchev.
The mare contains the second instance of a lunar pit on the moon and one of several outside the Earth to date.