This is the newest trail in the TVTA Marilla network. The trail may be used as a 1.5-mile trail from the kiosk at the beginning of the Indian Pipe Trail to a point on West Washington St. (Rt. 346) near the top of the hill. Alternately a northern fork of the trail leads to a grassy road. After 2/10-mile the Hidden Valley Passage resumes to the right and crosses a ridge to the Indian Pipe Trail. By turning south (right) on the Indian Pipe Trail a 3.6-mile loop can be walked. Most of the Hidden Valley Passage is on a one-mile section of late 1800s railroad grade that roughly parallels West Washington Street (Rt. 346). This old grade makes an easy walk and provides interest. Depressions of the ties still remain. Where the railroad crossed runs depressions in the earth mark where long-gone timber trestle bridges carried the rails from embankment to embankment. The remaining portions of the trail are single-track paths through mixed forest. Wooden walkways cross the wider wet areas and streams.