The park has an abundant variety of wildlife, many of them endangered. The existence of 33 species of mammals indicates a maintained high diversity, despite the environmental problems affecting the ecosystem. The park is home to 98 species of invertebrates, nine species of amphibians, 35 species of reptiles, more than 140 fish species and 199 birds, many of which are migratory, endemic and residents.
Mangrove forests, tropical dry forests and riparian forest cover most of the area. The mangroves cover a third of the area (12,000 hectares) and the three predominant species are: red mangrove, black mangrove, white mangrove and buttonwood.
In 2000 the park was designated a Biosphere reserve by UNESCO.