The Eno River State Park is one of the hidden gems in Durham, especially for outdoor recreation enthusiasts. From the official website:

The Eno River (map 300kb) begins in northwest Orange County, flowing eastward for approximately 33 miles until, along with the Little and Flat rivers, it becomes the Neuse and flows into Falls Lake. Its waters roll through wilderness; passing historic mill sites, river bluffs covered with flowering shrubs and fords used by early settlers. The river can run as swift as the wind and as gentle as a blowing breeze. Upstream, rapids smash against rocks daring to stand in the river's path. Further down the Eno meanders quietly through serene surroundings. The valley of the river is narrow and steep-walled. The rolling landscape is carved and sculpted by swift-flowing water. Eno River State Park lies here, in the beauty of more than 3,900 acres of natural resources. Five access areas - The Cabe Lands, Cole Mill, Few's Ford, Pleasant Green and The Pump Station - offer entry into this largely unspoiled river environment.

The park has a strong citizen advocacy group in the Eno River Association, which is a 501c3 non-profit conservation organization whose mission is to conserve and protect the natural, cultural and historic resources of the Eno River basin.  Since 1966, the Association has worked actively to protect the lands and waters along the Eno River and its tributaries.

Each summer, the park hosts one of the top music events in the Triangle in the Festival for the Eno. In 2011, the event featured over 90 performers on 4 stages. The event typically occurs over the 4th of July weekend. They are currently seeking volunteers and sponsors to make this years's event another success.

Location
Durham
Website
http://www.ncparks.gov/Visit/parks/enri/main.php