Best urban playground: National parks are rare in American cities; what further distinguishes Rock Creek Park (202-895-6070, www.nps.gov/rocr) is how quickly hikers find peace and quiet within its boundaries. Spilling 15 miles south from D.C.'s northern corner, the 1,754-acre park traces a stream valley along forests of maples, oaks, and sycamores, sheltering white-tailed deer and migratory birds. Three primary trails run through the park, a boon to D.C. residents.

Best lunchtime workout: With its egalitarian attitude and self-policing honor code, ultimate frisbee may be America's most democratic sport. Pioneered in the 1960s, this soccer-with-flying-discs game encourages participation (beginners welcome) and rewards players with a heart-healthy cardio session. Check the Web site of Washington Area Frisbee Club (301-588-2629, www.wafc.org) for matches and tournaments, or just arrive for pick-up games, with one of the best starting Fridays at noon on the National Mall near the National Museum of Natural History.

Best moonlight paddling: Hooting bard owls, leaping fish, beavers slapping the water with their tails to alert comrades to your presence—such reception awaits paddlers on moonlight kayak rides down Piscataway Creek, a Potomac tributary by Mount Vernon, George Washington's plantation 17 miles south of downtown. Atlantic Kayak (301-292-6455, www.atlantickayak.com) leads groups of all levels on excursions departing at sunset.

Just south of the National Mall, Tidal Basin Paddle Boats (202-479-2426, www.tidalbasinpaddleboats.com) rents two- and four-person boats for sunset rides around this lake-like tributary of the Potomac. Enjoy views of the Jefferson Memorial, the FDR Memorial, and others, which are even more impressive by the twilight’s last gleaming.