Rio São Miguel is a river located in the state of Alagoas in eastern Brazil, flowing from its headwaters within the state before emptying into the Atlantic Ocean near the coordinates 9°51′S 35°54′W. This coastal river system is characteristic of the northeastern Brazilian littoral zone, where freshwater and saltwater environments converge to create productive estuarine habitat. The river's proximity to the Atlantic makes it a dynamic fishery where marine species push well into the lower reaches, offering anglers a diverse mix of hard-fighting saltwater and estuarine targets in a tropical setting.