Snellius is a lunar impact crater located near the southeast limb of the Moon.

The rim of Snellius is heavily worn and eroded, with overlapping craterlets.

The western rim marks the start of the Vallis Snellius, one of the longest valleys on the Moon.

Just to the northwest is Snellius A, a crater with a notable ray system that overlaps the southwest reaches of Mare Fecunditatis to the north.

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