I really like Watkins Regional Park, they have many activities... they have a traint that goes around an area of the park, a carousel, a children's play area, sports fields, a nature center, and during the holiday season, they have the Festival of Lights that is awesome, any fees are very affordable (ie $5/car at Festival of Lights). I mostly visit the nature center, it's wonderful, geared for children mostly, has a small collection of animals, such as a terrapin, falcon, owls, frogs, a snake, birds of prey in rehab outside the rear of the nature center... Sometimes the trails are very muddy/boggy, and can not be traveled. I recommend people visit Watkins Regional Park in Upper Marlboro, MD.
5303 Chrysler WayUpper Marlboro, MD 20772
4200 Ritchie Marlboro RdUpper Marlboro, MD 20772