Things to do in Imperial County are listed by cities below such as El Centro, Calexico, Brawley, Imperial and Calipatria. Imperial County, California, lies at the southernmost part of California, just north of Mexico. Originally part of San Diego County, it is located inland, to the east of San Diego and to the west of Arizona. El Centro is the largest city in the county, followed by Calexico. Imperial County is home to the historic site of Fort Yuma as well as the famous Blue Angels of the US Navy. The Algodones Sand Dunes, Fossil Canyon, Painted Gorge, and the Anza-Borrego Desert State Park provide visitors with opportunities for hiking, wildlife viewing, and even fossil hunting. The majority of Salton Sea, an inland lake, is located in Imperial County and has several campgrounds, parks, and a national wildlife refuge for visitors to enjoy. Imperial Sand Dunes is a well-known OHV (off-highway vehicle) area for those with motorized vehicles optimized for sandy terrain. There are two other OHV areas including Superstition Mountain and Plaster City OHV. Visitors can also see the Salvation Mountain, which is a colorful, man-made mountain located near Slab City.