Middle Fork Trail #4001 is a 78-mile backpacking route through the Frank Church-River of No Return Wilderness that parallels the Middle Fork Salmon River from Boundary Creek to Big Creek Bridge, offering access to historic cabins, Native American pictographs, and opportunities to meet up with river rafting trips.

The trailhead at Middle Fork Transfer Camp provides toilet facilities, stock holding areas, and a ramp, with long-term parking available for boaters.

Hikers should be prepared for rockfall, downed trees, spring flooding, and wilderness conditions; the trail is typically cleared annually but requires proper permits, Leave No Trace practices, and self-sufficiency as cell service is unavailable.