Lacus Perseverantiae is a small 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...

 extending westward from the northwestern exterior of the crater Firmicus

Firmicus (crater)

Firmicus is a lunar crater that lies in the eastern part of the Moon's near side, so that from Earth it appears oval in shape due to foreshortening. It is, however, very nearly circular. The crater is located to the west of the Mare Undarum, and northeast of the similar-sized crater Apollonius. To...

, with smaller extensions to the northeast and northwest at the eastern terminus. Its name is Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 for Lake of Perseverance. The selenographic coordinates are 8.0° N, 62.0° E, and it has a length of 70 km, but a maximum width of less than 15 km.