Cabeza Prieta, Spanish for "dark head," refers to a lava-topped, granite peak in a remote mountain range in the western corner of the refuge. This rugged landscape is home to as many as 391 plant species and more than 300 species of wildlife. Visitors to Cabeza Prieta can enjoy plentiful hiking, photography, wildlife observation, and primitive camping opportunities. Visitors, however, are asked to avoid lingering near water holes, as wildlife depend on them for survival.

Organ Pipe Cactus National Monument is home to an extraordinary range of animals that have adapted themselves to the region's extreme temperatures, intense sunlight, and infrequent rainfall. Six varieties of rattlesnakes, as well as Gila Monsters and scorpions, can be found at Organ Pipe. Other residents include the roadrunner, western diamondback rattlesnake, red-tailed hawk, coyote, cactus wren, javelina, desert tortoise, Gila monster, Gila woodpecker and white-winged dove.

Founded in 1952, the Arizona-Sonora Desert Museum is a non-profit educational institution focusing on natural history and dedicated to fostering public appreciation, knowledge, and wise stewardship of the Sonoran Desert region.

On the basis of the Ley General del Equilibrio Ecológico y la Protección al Ambiente, this area just south of the Arizona - Sonora border was declared a biosphere reserve in 1993 because of the need to conserve a significant portion of the Sonoran Desert.

La Sierra de El Rosario and the volcanic shield are the two core zones of the reserve. Together they cover almost 40% of the reserve’s 714,557 hectares, thereby helping to conserve a number of volcanic formations such as 10 maars, more than 400 cinder cones, lava flows, and the Santa Clara volcano itself. El Pinacate experienced intense extrusive vulcanism four million years ago. Activity continued for approximately 2 million years and resulted in the extensive volcanic shield.

The Jesuit priest Francisco Eusebio Kino was the first to recognize the volcanic origin of El Pinacate and was responsible for naming the Santa Clara volcano. El Pinacate has a cultural history dating back approximately 20,000 years according to archaeological dating of artifacts. The San Dieguito complex and its rock-based artifacts found in the volcanic soil have bbeen documented as the earliest signs of human occupation in the area. Other cultures subsequently appeared in El Pinacate region such as the Amaragosa group, the Hia’ Ced O’odham (the Sand People or Pimas Altos), and the present day population of Tohono O’odham that reside on both sides of the international border.

The reserve also contains the largest field of active, stabilized sand dunes in North America. El Gran Desierto de Altar covers approximately 5,000 square miles.

The Pinacate, which is 30 kilometers north of Puerto Penasco, is an ecological reserve comprised of 28,600 hectares of land. One of the most beautiful and isolated desert landscapes, the reserve features majestic mountains, hundreds of volcanic cinder cones and lava flows, sand dunes, and washes. The landscape of the area leaves the visitor feeling as though they may have landed on the surface of the moon. In fact, astronauts visited the Pinacate to familiarize themselves with a lunar-type landscape before heading for the moon.

The Upper Gulf of California and Colorado River Delta Biosphere Reserve is one of the richest coastal ecosystems worldwide. This is due to its high productivity and great biodiversity, the presence of a great number of land and marine species exclusive for the region, as well as others that are endangered or threatened.

The reserve was established in June 1993 and includes an area of 934,756 hectares with a “core zone” mainly within the river delta and a surrounding “buffer zone”. The main objective is to achieve present and future conservation, sustainable use and integrity of the terrestrial and marine wildlife in their natural ecosystems as well as promote the social development of the local communities and users of the natural resources.

The core zone is where most of the protection activities taker place and the buffer zone where the productive activities are carried out/ The conservation of natural resources is important, because it will allow and orderly utilization of the natural resources that may have economic and biological importance for the region. As a Biosphere Reserve, this area will strengthen the sustainable economic activities of the region promoting the economic welfare of the local inhabitants through the rational use of the resources.