Rio Mampituba is a 62-kilometer river that originates in the Serra Geral highlands and flows eastward to the Atlantic Ocean at Torres, where it meets the sea. In its lower reaches, the river forms the natural border between the states of Santa Catarina and Rio Grande do Sul, making it a geographically distinctive waterway in southern Brazil. The river drains a basin covering approximately 11,300 hectares with a perimeter of 14.5 kilometers, and its watershed supports a population of over 12,000 people. The Mampituba sits within the Tramandaí-Mampituba Ecoregion, a biogeographically significant freshwater zone recognized for its high endemism of native fish species. The lower course of the river remains largely navigable, though the bar at its mouth is known to be unstable.