The Lago Piratuba Biological Reserve, which covers 392,469 hectares (969,810 acres), was established by decree of 16 July 1980.

[3] The region is flat, formed by sediments of mixed river and ocean origin, and subject to periodic flooding.

Fauna is also very diverse, including green sea turtle (Chelonia mydas) and leatherback sea turtle (Dermochelys coriacea), migrating or resident birds such as pelicans and osprey, and mammals such as capybara, otter and racoon in the flooded fields.

[7] The main objective is to protect the flora and fauna of the Amazon ecosystem in its transition into the lagoon zone.

[3] Protected species are jaguar (Panthera onca), giant otter (Pteronura brasiliensis) and Amazonian manatee (Trichechus inunguis).