St. Mary's River State Park is a park that is not well known, but a real treasure. The park is located on the headwaters of the St. Mary's River, and is divided into two sites. This 7.5 mile trail encircles the 250 acre St. Mary's Lake. First time hikers should allow extra time for interesting detours.
Three miles north of Great Mills, 24 miles north of Point Lookout State Park, off MD Route 5 on Camp Cosoma Road
http://www.tripleblaze.com/trail.php?c=3&i=4299