Near Sun Valley, the 4 mile Proctor Mountain Loop is a challenging horseback ride up 2,000 feet over 2 miles. Use caution since this route is very popular with mountain bikers.
Starting from the Trail Creek Cabin parking area. From here, cross Trail Creek on the XC ski bridge and head upstream on the dirt road behind the ampitheatre. Once in the trees, follow the trails to the right. This leads up the mountain. The horseback riding route back down is awesome.
Overall, Proctor Mountain Loop is the 17th most popular horse trail of all 56 horseback rides in Idaho.