Cabeza Prieta National Wildlife Refuge
This 860,000-acre national wildlife refuge, about 5 miles (a 10-minute drive) from Ajo, was established in 1939 as a preserve for endangered bighorn sheep and other Sonoran Desert wildlife, including the long-nosed bat and the Sonoran pronghorn deer, the fastest mammal in North America. People come here for hiking, photography, and primitive desert camping.
A free permit, essentially a "hold-harmless" agreement, is required to enter, and only those with four-wheel drive, high-clearance vehicles, or all-terrain vehicles—needed to traverse the rugged terrain—can obtain one.
Pick up a permit from the refuge's visitor center in Ajo, about a mile north of the downtown plaza.