The wild water and craggy landscape of Great Falls Park (©Jared Browarnik, Flickr)
Only 15 miles from D.C.'s urban bustle, an 800-acre national park where the Potomac River plunges some 76 feet through narrow Mather Gorge. Ranger-led talks and nature walks. Fifteen miles of trails, picnic areas and remnants of the 18th-century Patowmack Canal. Open daily. $7 per individual, $15 per car.