Sinus Asperitatis is an area of lunar mare

Lunar mare

The lunar maria are large, dark, basaltic plains on Earth's Moon, formed by ancient volcanic eruptions. They were dubbed maria, Latin for "seas", by early astronomers who mistook them for actual seas. They are less reflective than the "highlands" as a result of their iron-rich compositions, and...

 that extends southward from the Mare Tranquillitatis

Mare Tranquillitatis

Mare Tranquillitatis is a lunar mare that sits within the Tranquillitatis basin on the Moon. The mare material within the basin consists of basalt formed in the intermediate to young age group of the Upper Imbrian epoch. The surrounding mountains are thought to be of the Lower Imbrian epoch, but...

 until it joins the Mare Nectaris

Mare Nectaris

The Sea of Nectar is a small lunar mare or sea located between the Sea of Tranquillity and the Sea of Fecundity . Montes Pyrenaeus borders the mare to the west and the large crater near the south center of the mare is known as Rosse...

 to the southeast. It is bordered along the western and eastern sides by continental regions of irregular terrain. The selenographic coordinates of this feature are 3.8° S, 27.4° E, and it has a diameter of 206 km.

In the northern part of this mare is the small crater Torricelli

Torricelli (crater)

Torricelli is a lunar crater in the eastern part of the Sinus Asperitatis, to the south of the Mare Tranquillitatis. The western rim of the crater is broken open and joined to a smaller crater to the west. The entire formation has a pear-shaped appearance...

. At the southern end is the prominent crater pair of Theophilus

Theophilus (crater)

Theophilus is a prominent lunar impact crater that lies between Sinus Asperitatis in the north and Mare Nectaris to the southeast. It partially intrudes into the comparably sized crater Cyrillus to the southwest. To the east is the smaller crater Mädler and further to the south-southeast is Beaumont...

 and Cyrillus

Cyrillus (crater)

Cyrillus is a lunar impact crater located on the northwest edge of Mare Nectaris. Intruding into the northeast rim is the equally large, and younger crater Theophilus. To the south is another prominent crater named Catharina. Together these three craters form a prominent trio in the southeast...

. On the border between Sinus Asperitatis and the Mare Nectaris is the crater Mädler

Mädler (lunar crater)

Mädler is a lunar impact crater located on the mare that joins Sinus Asperitatis in the north to Mare Nectaris to the southeast. To the west is the prominent crater Theophilus, and Mädler lies amidst the outer rampart....

.