Lake Hartwell is a man-made reservoir bordering Georgia and South Carolina and encompassing parts of the Savannah, Tugaloo, and Seneca rivers. Lake Hartwell is one of the Southeastern United States' largest recreation lakes. The lake was created by the construction of the Hartwell Dam, completed in 1962 and located on the Savannah River seven miles (11 km) below the point at which the Tugaloo and Seneca Rivers join to form the Savannah. Extending 49 miles (79 km) up the Tugaloo and 45 miles (72 km) up the Seneca at normal pool elevation, the lake comprises nearly 56,000 acres (230 km2) of water with a shoreline of 962 miles (1,548 km). The entire Hartwell "Project" contains 76,450 acres (309 km2) of land and water. I-85 bisects Hartwell Lake and makes the area easily accessible to visitors.

The Savannah River is a major river in the Southeastern United States, forming most of the border between South Carolina and Georgia. Two tributaries of the Savannah, the Tugaloo River and the Chattooga River, form the northernmost part of the state 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 301 miles (484 km) long. The Savannah was formed by the confluence of the Tugaloo River and the Seneca River. Today this confluence is part of 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.