A Saudi prince once visited the Sonoran Desert. The Saudis are experts on the desert. Upon his first view of the Sonoran, he exclaimed, "This is not a desert. This is a garden." Organ Pipe Cactus National Monument's 516 square miles are devoted to preserving a verdant lower Sonoran Desert landscape, home to its namesake organ pipe cactus. The monument is also an International Biosphere Reserve. The Ajo Mountain Loop is the monument's most popular and easiest drive.
The 20-mile loop crosses a valley landscape filled with forests of stately saguaro cacti set against the backdrop of the rugged Ajo Mountain Range. The winding climb through the narrow scenic Diablo Canyon sets the stage for your first look at the Ajo Wondow, a double arch high on a volcanic cliff. Arch Canyon is an easy, popular hike to better view this geologic oddity. Skirting the western slope of Ajo Mountain, the trailhead for the very strenuous Bull Pasture hike has picnic tables and a vault toilet. It's a great area to stop, stretch your legs, and admire the rugged mountainous landscape.