El Pinacate y Gran Desierto de Altar Biosphere Reserve, Biosphere reserve in Sonora, Mexico

El Pinacate y Gran Desierto de Altar is a biosphere reserve and UNESCO World Heritage Site in Sonora, just south of the Arizona border and north of Puerto Peñasco. Its Santa Clara volcanic system includes three peaks, the highest being Cerro del Pinacate at 1,190 m. Around the volcanic shield lie extensive active dunes and craters such as El Elegante, Cerro Colorado, MacDougal and Sykes.

Volcanic activity in the Sierra Pinacate began about 4 million years ago and last occurred roughly 11,000 years ago. In 1540 the explorer Melchor Díaz may have been the first European to see the range, and in 1698 the Jesuit Eusebio Kino climbed the highest peak and named it Cerro Santa Clara. From 1965 to 1970 NASA sent astronauts here to train for lunar walks.

The Tohono O'odham people hold this land sacred, viewing Pinacate Peak as central to their creation story. This spiritual connection shapes how they understand and relate to the region.

Access is via the Biological Station at kilometer 51 on Highway 8 between Sonoyta and Puerto Peñasco, where visitors must register before entering. The cooler months are the most comfortable for visiting; carry plenty of water and sun protection.

The reserve protects the greatest concentration of maar craters on Earth, including El Elegante, Cerro Colorado, MacDougal and Sykes. Its volcanoes erupted sporadically for about four million years, with the most recent activity around 11,000 years ago.