The Rimae Hippalus are three concentric graben along the Western borders of Mare Humorum. They have a lenght oof about 240km. The most western graben runs across lave flooded crater Hippalus in the North.
The Southern parts run over the higlands between Mare Humorum and Palus Epidemiarum. The most western graben is interrupted by the craters Campanus A and Agatharchides A.
Rimae Hippalus is best observed during Waxing gibbous Moon or waning crescent Moon.

A fellow observer/imager compared the Rimae Hippalus to claw marks left on the lunar surface by a bear.