The Mapuá River rises on the island of Marajó in the delta region where the Amazon and Tocantins rivers empty into the Atlantic Ocean.

It runs along the southern boundary of the Mapuá Extractive Reserve.

The Mapuá is a left tributary of the Aramã, which forms the northern boundary of the reserve.

[1] The reserve is mostly lowland floodplain, with some terra firma in the centre of the territory.

This article related to a river in Pará, Brazil is a stub.