St. Mary's River Park features 8 miles of hiking trails near Lexington Park, MD.
How to get there:<br />Head North on Route 5 from Lexington Park or South on Rt. 5 from D.C. Exit at Camp Cosoma Rd and follow signs to St. Mary's Park. Once in the park, drive to the far side and park by the bathrooms. A sign marks the trail to the right.<br />I snagged directions from another site just to make sure they were accurate.
http://www.tripleblaze.com/trail.php?c=3&i=1122