The Big Satilla River is a river in South Georgia. It rises in Ben Hill and Coffee counties and flows southeast for 260 miles (420 km). It is one of Georgia's 14 major watersheds. It empties into the Atlantic Ocean through St. Andrew Sound, north of Cumberland Island. Cumberland Island is one of the Sea Islands of the southeastern United States and is the largest in terms of continuously exposed land. French explorer Jean Ribault named it Riviere Somme, but a Spanish explorer, St. Illa, gave the river his own name, which was converted from St. Illa to Satilla by English usage.