Cerro de la Calavera, or Mount Calavera, is a 513-foot volcanic hill in Carlsbad, California, and one of only three volcanic plugs in Southern California. An ancient plug dome volcano formed during the subduction of the Farallon Plate, it last erupted about 22 million years ago. Its distinct shape makes it a prominent feature in the surrounding urban landscape. The hill now stands within Lake Calavera Preserve, where maintained trails allow access to the ancient formation. At its base are Lake Calavera and its dam, and the hill remains an easily recognized local landmark.