St. Marks River
 The St. Marks River is a river in the Big Bend region of Florida. It has been classified by the Florida Department of Environmental Protection as an Outstanding Florida Water and is the easternmost river within the Northwest Florida Water Management District.The St. Marks River begins in eastern Leon County Florida and flows 36 miles (58 km) through Leon and Wakulla counties into Apalachee Bay an arm of the Gulf of Mexico. It has a drainage basin of 1150 square miles (3000 km2) in size.