You can reach wild places in the Washington area by Metro. Hike (or bike) without needing a car.
Here is one a month, suggested by the Audubon Naturalist Society:
DC Blue Line/ DC Orange Line
To reach the Potomac River and Thompson Boat Center, go west
(right) 1 block on I St. plaza and left 2 blocks on New Hampshire
Ave. Cross Virginia Ave., turn right (NW), and walk 1 block along
Virginia Ave. to Rock Creek Parkway. Rent a boat here to see
Canada geese and other wildlife along the river and around
Roosevelt Island, or take 30th St. north from Thompson's (by the
big sundial) to the Chesapeake & Ohio (C&O) Canal. The towpath
leads through the heart of Georgetown and into riverside forest
habitat after 0.5 mi. (The trail ends 184 miles upstream at
Cumberland, Md., somewhat more than a day's hike.)
College Park-U of Maryland
MD Green Line
Exit the station left up escalator. Cross lot to Paint Branch
Parkway. Turn right, go 0.4 mi. to Paint Branch, a tributary of
the Anacostia River. Watch for eastern bluebirds, and look under
logs for red-backed salamanders at the edge of the woods. Follow
the paved path upstream (left) 0.5 mi. to Lake Artemesia, whose
38 acres are home to water lilies, herons, ducks, frogs,
dragonflies, and some catchable fish. Downstream (right) it's
about 2 miles to the colonial port of Bladensburg and the broad,
tidal Anacostia River.
MD Green Line
Travel southeast 0.2 mi. along Jamestown Rd. to the paved trail
at the intersection with Queens Chapel Rd. (Rte. 500). Turn right
and follow the trail west through flower-filled meadows as the
trail winds along the Northwest Branch of the Anacostia River.
Watch for monarch butterflies feeding and flying here on warm
sunny days. Continue 0.3 mi. along the trail into a forest whose
brushy edges include blackberries and other fruits favored by
birds and hikers alike. A bit farther is the junction with Sligo
Creek. Trails continue along both branches through fields and
forests for many miles.
Dunn Loring -- Washington & Old Dominion Regional Park
VA Orange Line
Walk from the station 3/4 mi north to reach the W & OD trail.
The former railroad bed is now a park, with a paved trail. You
can make this a loop by hiking 4-1/2 mi west (left) to the East
Falls Church Metro station and returning from that station.
Watch for woodchucks and bluebirds, but the park is urban.
Another 5 miles west will put you in pleasant patches of forest
and meadow where wildflowers and butterflies abound.
MD Red Line
Go to the end of the pedestrian tunnel and take the stairs
outside the station entrance. Go east across Georgia Ave. and
cross to the south side of Forest Glen Rd. Proceed 0.5 mi. down
to the paved Sligo Creek Trail, which leads past a mixture of
meadows, forests, and wetlands. Watch for a variety of
butterflies visiting the meadow flowers and for white-tailed deer
at the edge of the woods. Follow the path about 3 miles upstream
(left and north) to reach Wheaton Regional Park, which features a small
lake, extensive hardwood forests, Brookside Nature Center, and
Brookside Gardens. Downstream it's about 6 miles to the West
Hyattsville Station (MD Green line).
Glenmont -- Brookside Gardens
MD Red Line
The Metro station is just north of the Glenmont Center (shopping mall), making the first part of
the trip an unpleasant hike. Get your orientation upon leaving the station by locating a tall water
tower on the other side of Georgia Ave. That tower is to the west. Walk west, to Georgia then
walk south (left) down Georgia Ave. For safety's sake, walk around (not through) the broad
parking lots using the sidewalk in front of the shops. At the southeast corner of the lots, use the
crosswalk and traffic signals to cross Randolph Road. To enter Wheaton Regional Park, you still
must walk south and east away from the traffic, several blocks through residential neighborhoods.
Brookside Gardens, at the north edge of the Park, offers ponds, fields, and formal gardens.
Nearby, see ducks, woodpeckers, deer, or wait until dusk to watch for bats and flying squirrels.
After dark in the holiday season, visit the Garden's elaborate display of lights.
VA Blue Line
Exit the station toward the Lincoln Memorial. Cross the street
and go east (left) 0.3 mi. (use GW Parkway crosswalks) to the
paved Mount Vernon Trail, which follows the Potomac River north
to Roosevelt Island and south 0.7 mi. to the Lyndon Baines
Johnson Memorial Grove, an attractive patch of white pine, willow
oak, and cottonwood trees. Visit the quiet river channel behind
the grove to watch great blue herons hunting fish and painted
turtles basking on the logs. This popular trail continues past
the National Airport Station (VA Blue and Yellow lines) (about 3
mi. south), goes through Old Town Alexandria, then continues to
Dyke Marsh, one of the areas most beautiful and vibrant wetlands.
DC Green Line
Go west (right) one block on M St., turn south (left) 0.2 mi. on
6th St. and follow the paved walkway to the Washington Channel of
the Potomac River. Once polluted and lifeless, the Potomac is now
a vibrant living river. Watch the fish jump, and search the
skies for bald eagle, osprey, and peregrine falcon. Walk down
Water St. 0.5 mi. to 9th St. Turn right and cross Maine Ave.
Follow the footpath to the pedestrian walkway along the high
bridge over the Channel. Or reach the walkway from the L'Enfant
Plaza station (DC Green, Orange, Blue, and Yellow lines). At the
far side is East Potomac Park, whose southern tip is Hains Point,
1.5 mi. from the bridge. Scan the meeting point of the Potomac
and Anacostia Rivers during the colder months to see a variety of
gulls and waterfowl.
East Falls Church -- Four Mile Run Park
VA Orange Line
Head south (right) one block on Tuckahoe St. Continue on the
paved path to Four Mile Run Park. Bear right at the fork just
beyond the bridge crossing Van Buren St. to the interpretive
trail. Tall maple and ash trees shade the creek, where cardinals
and goldfinches sing from the shrubs. The paved Washington & Old
Dominion Railroad Trail (W&OD) runs adjacent to the station's
DC Red Line
Exit on east side of Connecticut Ave. Travel 0.2 mi. north
(right) to Melvin Hazen Park, and follow the foot trail down a
wooded ravine beneath beech and oak trees more than 100 feet
tall. Watch for wildflowers in spring and for the wood thrush,
D.C.'s official "state" bird, throughout warmer months.
Woodpeckers are common year round. This 0.5 mi. trail connects to
trails in Rock Creek Park. To see exotic animals, go 0.4 mi.
south on Connecticut Ave. to reach the National Zoo. The Zoo
connects to Rock Creek Park, making a loop hike of about 3 miles.
MD Red Line
Exit east from the station. Go past the parking garage to Redland
Rd. Go left (NE) on Redland to the Crabb's Branch Way
intersection. Two ponds are visible from the roadside. Check here
for water birds, frogs, turtles, and dragonflies. Diagonally
across the Redland/Crabb's Branch Way junction lies an open mix
of woods and fields where white-tailed deer and foxes roam.
Listen for warblers here in the spring. Go 0.3 mi. east on
Redland Rd. and then right 1.5 mi. on Needwood Rd. to reach Lake
Needwood and Rock Creek Regional Park, where ducks patrol the
lake, woodchucks frequent the meadows, and chipmunks abound in
VA Blue Line/VA Orange Line
Exit to Moore St. and head north (right) 1 block to 19th St.,
then east (right) 1 block to N. Lynn St. Follow signs north
(left) 2 blocks to paved Hiker/Biker trail that leads 0.3 mi. to
Theodore Roosevelt Island. Most of this 88-acre island is
protected natural habitat, a tribute to the great conservationist
President. Foot trails (bicycles prohibited) around the island
lead through a mature floodplain forest where wildflowers and
songbirds abound in spring. Island swamps and marshes are home to
frogs, muskrats, and more. The Potomac Heritage Trail begins at
the Roosevelt Island parking area. This foot path follows the
Potomac upriver 10 mi. to the Scott's Run Nature Preserve.