The Savannah River is a major river in the southeastern United States, forming most of the border between the states of South Carolina and Georgia. Two tributaries of the Savannah, the Tugaloo River and the Chattooga River, form the northernmost part of the border. The Savannah River drainage basin extends into the southeastern side of the Appalachian Mountains just inside North Carolina, bounded by the Eastern Continental Divide. The river is around long. It is formed by the confluence of the Tugaloo River and the Seneca River. Today this confluence is submerged beneath Lake Hartwell. The Tallulah Gorge is located on the Tallulah River, a tributary of the Tugaloo River that forms the northwest branch of the Savannah River.