The Altamaha river proper begins at the confluence of the Ocmulgee, Oconee and Ohoopee rivers, in the area south of Vidalia, and it runs southeast for about 220 km (140 mi), emptying into the Atlantic Ocean near Brunswick.
Although used in the 19th century as a route for commerce between central Georgia and the coast, the river is nearly entirely still in its natural state, and was designated a bioreserve by The Nature Conservancy in 1991. Over 100 rare or endangered species may be found in the river basin, and the delta is a major stopover for many species of migratory birds.