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 Yucat&aacute,n peninsula, this biosphere reserve contains tropical forests, mangroves and marshes, as well as a large marine section intersected by a barrier reef. It provides a habitat for a remarkably rich flora and a fauna comprising more than 300 species of birds, as well as a large number of the region`s characteristic terrestrial vertebrates, which cohabit in the diverse environment formed by its complex hydrological system.