South Boundary Trail: South Entrance-Harebell is a 24.28-mile out-and-back foot trail in Yellowstone National Park, Wyoming. It climbs 839 ft to a high point of 7,627 ft. Difficulty: very strenuous, from the NPS hiking-rating formula.

Open South Boundary Trail: South Entrance-Harebell on Trailbound's interactive map to see the full route, the elevation profile, today's forecast and any park alerts for Yellowstone. Yellowstone has permits or reservations for some areas: see the Yellowstone page for what's needed.