Hikes, nature classes, environmental volunteer opportunities, and related events in the Washington, DC metro area

There is a wealth of organizations in the DC area that organize walks, classes, and other events on a regular basis. We used to try to keep a calendar of them all, but there's just too much going on. See for yourself!

Service Opportunities
Chesapeake Bay Foundation
Friends of Rock Creek Park
Arlingtonians for a Cleaner Environment
Anacostia Watershed Society
Anacostia Riverkeeper
Casey Trees 
C&O Canal Trust
Potomac Conservancy

Plants and Fungi
Matt's Habitats Wild Edibles & Nature Walks
Maryland Native Plant Society Meetup
Virginia Native Plant Society
Mycological Association of Washington
Audubon Naturalist Society 
Casey Trees
Ancestral Knowledge
Mid-Atlantic Primitive Skills Events

Birds
DC Audubon Society
Prince George's Audubon Society Field Trips
Montgomery Bird Club
Audubon Naturalist Society - birding
Audubon Society of Northern Virginia

Hiking Clubs and Meetups
Northern Virginia Hiking Club
Sierra Club Potomac Regional Outings
Center Hiking Club
Potomac Appalachian Trail Club (PATC)
Capital Hiking Club
Appalachian Mountain Club
Washington Women Outdoors
Maryland Outdoor Club
Wanderbirds
Meetups

Activities at Specific Parks
Local nature centers
Rock Creek Park
Huntley Meadows
Potomac Overlook
Jug Bay
Great Falls VA
Arlington parks
Patuxent Wildlife Research Center
Meadowlark Botanical Garden
National Arboretum
C&O Canal Association

Occasionally Relevant Lectures
National Geographic
Museum of Natural History
US Botanic Garden

Planetariums in the DC area