Lake Ilopango is a crater lake which fills a scenic 8 by 11 km (72 km² or 28 sq mi) volcanic caldera in central El Salvador, on the borders of the San Salvador, La Paz, and Cuscatlán departments. The caldera, which contains the second largest lake in the country and is immediately east of the capital city, San Salvador, has a scalloped 100 m (330 ft) to 500 m (1,600 ft) high rim. The lake is known for being a possible source for the extreme weather events of 535–536, and locally Ilopango lake is known for being a hot spot for UFO sightings.