The St. Marys River (sometimes spelled as the St. Mary's River) is a river, approximately 90 mi (144 km) long, in the southeastern United States. It forms the eastern portion of the boundary between the U.S. states of Georgia and Florida, which continues west from its source.
It rises in the southeastern Okefenokee Swamp, and flows S, then E, then N, then ESE and flows into the Atlantic Ocean near St. Marys, Georgia and Fernandina Beach, Florida.
