Mare Crisium, or the Sea of Crises, is a large lunar mare located on the Moon's surface. It is approximately 555 kilometers wide and is one of the prominent dark plains formed by ancient volcanic activity. This area is characterized by its relatively smooth terrain and is surrounded by rugged highlands. The mare is situated in the northeastern part of the Moon and is easily visible from Earth. It features several craters, including Crisium, which is the largest and most notable. Mare Crisium is of interest to scientists studying the Moon's geological history and volcanic processes.