It protects the Marajó Archipelago, made up of marine fluvial islands in the area where the Amazon and Tocantins rivers converge and flow into the Atlantic.

[1] Vegetation includes alluvial and lowland dense rainforest, savannah, field, and pioneer formations in floodplains, salt marshes, mangroves and sandbanks.

Buffalo were introduced when a ship carrying them from India to French Guiana was shipwrecked off Marajó island, and they found the environment of flooded fields and abundant vegetation ideal.

[1] Objectives are to develop and implement ecological and economic zoning aimed at conserving biodiversity and improving the quality of life of the population.

Other goals are to preserve endangered species and representative samples of ecosystems, and support scientific research, environmental education and ecotourism.