It was declared a Protected Natural Area since 1996, its extension is 206,581 hectares and includes part of the Sea of Cortez, mangroves and coastal dunes, as well as the ecological reserves of the islands of Coronado, Carmen, Danzante, Monserrat and Santa Catalina.

The marine flora is represented by 161 species of macroalgae inhabited by a large number of invertebrates and crustaceans, fan corals, spiny clams, sea urchins, stars, hermit crustaceans, ghost shrimp, to name a few.

The islands are inhabited by a large number of endemic terrestrial species and are also a refuge for migratory birds. Blue whales with young calves are regularly observed in this part of the Gulf of California.