From Seattle, head southeast and pick up Route 169 to Enumclaw-Franklin Road. Five miles down, you'll find some unmarked trailhead gates. See the gate leading toward the power lines? That's the Mercury Mine trail. It drops you at the edge of the Green River Gorge, a 300-foot-deep gash. It's only 27 miles from the city, but you wouldn't know it from the Class IV whitewater (River Recreation; riverrecreation.com) and old hunters' paths in the damp primeval forest.