Lagoa do Saguaçu is a coastal lagoon forming a significant part of the Babitonga Bay estuarine complex on the northern coast of Santa Catarina, Brazil. This brackish water system is situated at sea level and flows through a relatively flat, low-lying area near the city of Joinville. As an estuarine environment, it is a transitional zone where freshwater from contributing rivers mixes with saltwater from the Atlantic Ocean, creating a rich and productive ecosystem that supports diverse aquatic life. The lagoon ultimately drains into the larger Babitonga Bay, which has historically served as a vital waterway for navigation and fishing in the region.