Annular lake

An annular lake is a circular lake caused by the impact of a meteor.

One of the largest annular lakes is Lake Manicouagan in Canada. The crater is a multiple-ring structure about 100 km (60 mi) across, with its 70 km (40 mi) diameter inner ring its most prominent feature; it contains a 70 km (40 mi) diameter annular lake, surrounding an inner island plateau, René-Levasseur Island. It is the earth's sixth-largest confirmed impact crater according to rim-to-rim diameter.

Another example is the Siljan Ring.