The Flume Gorge is one of the classic walks in Franconia Notch, a narrow granite gorge with cascades, waterfalls, mossy walls, and a boardwalk that lets you move through the tightest section without scrambling over wet rock.
The route is seasonal and there is an entrance fee, but it is an easy way to see the White Mountains up close without committing to a full mountain hike. Allow time for the loop path rather than treating it as a roadside viewpoint.