The Harquahala Mountain Byway runs adjacent to the 22,880-acre Harquahala Mountains Wilderness, which lies in Maricopa and La Paz counties. The wilderness is perfect for nature lovers as it is filled with wildlife and has extremely diverse native plants. It even contains a rare species of cactus. For those who love to hike or backpack, the area provides a rugged landscape and a sheltered canyon called Brown's Canyon. To reach the summit, plan on driving on a rough steep road with fallen rock dotting the corridor.
The Harquahala Mountains Wilderness is part of Arizona's largest mountain range, which contains Harquahala Peak. The peak is 5,691 feet tall and for the last 0.75 miles ascends sharply for 1,400 feet.
On top of Harquahala Peak is an old observatory that was built in the 1920s by the Smithsonian Astrophysical Observatory. The purpose of the observatory was to measure and record solar activity, using panels of large thermometers. The data was used to help forecast the weather.