Finsen is a lunar impact crater that is located in the southern hemisphere, on the Moon's far side.

The rim is circular but somewhat uneven along the edge, with outward protrusions along all sides except to the north and northwest.

At the midpoint of the crater is a central peak formation, occupying an area of roughly 15 km.

This central peak has a higher albedo than the surrounding floor or rim, giving a lightened appearance.

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Finsen.