The Rio Maracanã is a meandering river in the state of Pará, Brazil, rising in the south of the município of Castanhal and flowing in a northeast direction until it empties into the Atlantic Ocean at Maracanã, Pará. In its lower reaches, the main channel varies in depth from 15 to 20 metres (49 to 66 ft), which reflects the substantial tidal and fluvial influence characteristic of rivers in this part of the Amazon coast.

Water levels follow a pronounced seasonal pattern. The river is at its lowest between September and October, and reaches its highest levels between February and April. Paddlers planning a trip should factor this seasonal variation into route planning, as low-water periods may expose shallows or alter navigable channels, while high-water months bring significantly greater volume and current. The main tributary, the Caripi River, enters the Maracanã from the left bank and represents a notable confluence along the river's course.

The town of Santarém Novo lies along the river and provides a point of human activity and potential access. The river's meandering character through this coastal region of Pará gives it a gradual, winding course rather than a swift or technical one, consistent with the low-gradient terrain of the northeastern Pará coast. The mouth at Maracanã, Pará, opens to the Atlantic, meaning paddlers approaching the lower reaches should be attentive to tidal influences, which can significantly affect current direction and water levels in estuarine sections.