界海
Ibn Yunus is the remains of a flooded lunar impact crater. It lies on the far side of the Moon, just past the eastern limb. It can only be viewed from Earth under conditions of favorable libration and lighting, and even then it is seen from the edge. This feature is attached to the east-southeastern outer rim of the flooded crater Goddard. It lies within the Mare Marginis, a lunar mare along the eastern limb.