Watkins Regional Park 
301 Watkins Park Drive
Upper Marlboro, MD 20774
301-218-6700
http://outdoors.pgparks.com/3204/Watkins-Regional-Park
Park: Hike, Picnic, Playground, Tennis, Walk
The largest nature center in the metropolitan area, boasting live animals, auditorium, large nature exhibit area, crafts and exhibits. There is also 6 miles of park trails to explore nature.