The St. Marks Wilderness Area is located at the eastern edge of the Florida Panhandle on the Gulf coast approximately 25 miles south of Tallahassee. The wilderness is part of the 68,931 acre St. Marks National Wildlife Refuge. The wilderness area consists of approximately 17,745 acres of salt water bays, estuaries and brackish marshes. The wilderness is divided into two units: the St. Marks unit to the east and a smaller unit to the west near the Ochlockonee Bay. The IMPROVE site is located in a forest clearing 3 miles south of the visitor center at the refuge near highway 59. The IMPROVE site is located at an elevation of 8 m MSL. The state of Florida DEP operates an ozone and meteorological station within close proximity.