Conejo Mountain is an 1,814-foot peak in Ventura County near Camarillo, marking the western end of Conejo Valley beside the Santa Monica Mountains and the eastern edge of the Oxnard Plain, where U.S. Route 101 climbs the steep Conejo Grade. Geologically, it began as a large volcano about 14 million years ago, later lay beneath sea level, and has been extinct for millions of years. In modern times, mining has operated there since 1959, with most of the mountain owned by Pacific Rock. Public agencies have also sought to manage the area as protected open space, with trails approaching from nearby parks and open-space lands.