This archipelago is part of a submerged mountain range, with the four islands representing the peaks of volcanoes emerging above sea level. The islands provide critical habitat for a range of wildlife and are of particular importance for seabirds.

The 714,566 hectare site comprises two distinct parts: the dormant volcanic Pinacate Shield of black and red lava flows and desert pavements to the east, and, in the west, the Gran Altar Desert with its ever changing and varied sand dunes that can reach a height of 200 metres.

The site comprises 244 islands, islets and coastal areas that are located in the Gulf of California in north-eastern Mexico.

The 56,259 ha biosphere lies within rugged forested mountains about 100 km northwest of Mexico City.

In the language of the Mayan peoples who once inhabited this region, Sian Ka'an means 'Origin of the Sky'. Located on the east coast of the Yucatán peninsula, this biosphere reserve contains tropical forests, mangroves and marshes, as well as a large marine section intersected by a barrier reef…

Located in the central part of the peninsula of Baja California, the sanctuary contains some exceptionally interesting ecosystems.