The Altamaha River system starts with the Ocmulgee and the Oconee rivers. Where the Ocmulgee and Oconee join in central Georgia near Lumber City, the Altamaha begins its slow trip to the Atlantic. The area is nearly as remote and wild now as it was when the British first came to Georgia. During the days of the great lumber camps, logs floated down the Altamaha to Darien to be milled.

To the southeast, the Altamaha creates a wide delta as it approaches the sea, like larger rivers such as the Mississippi. The Altamaha is a tidal river, with tides affecting the river's height up to 40 miles (64 kilometers) inland from the Atlantic. The flood plain is about 12 miles (19 kilometers) wide and provides rich soil for growing rice. The area is dotted with small islands, most of which are covered with wildlife and an odd mix of plants.