Hyginus is a lunar caldera located at the east end of the Sinus Medii.

[1] Its rim is split by a 220 kilometer-long rille, Rima Hyginus, that branches to the northwest and to the east-southeast.

[citation needed] Hyginus is one of the few craters on the Moon that was not created as a result of an impact, and is instead believed to be volcanic in origin.

Major objectives would have included examining and sampling the Cayley Formation and dark overlying rocks, the crater rim and floor, and other possible volcanic features in the area.

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