Rio Portinho is a river located in the state of Piauí, Brazil, situated in a coastal and estuarine landscape that includes nearby lagoons, islands, and tidal waterways. The river flows through a region characterized by a rich mosaic of aquatic environments, with the associated Lagoa do Portinho lying in close proximity. This area of Piauí's coastline is part of a broader network of rivers, channels, and wetlands that support diverse aquatic life and offer anglers access to both freshwater and brackish fishing opportunities. The surrounding geography includes notable features such as salinas, igarapés, and a series of islands that define the character of this deltaic coastal zone.