The Boise National Forest is a US national forest located north and east of the city of Boise, Idaho. It is about 2,612,000 acres (10,570 km²) in size, ranging in elevation from 2,600 to 9,800 feet (800 to 3000 m). The mountainous landscape developed through uplifting, faulting, and stream cutting. Most of the land lies within the Idaho Batholith, a large and highly erodible geologic formation. The major rivers that run through it include the Boise, the Payette and the South and Middle forks of the Salmon River. Portions of the Frank Church-River of No Return Wilderness, the Sawtooth Wilderness, and Sawtooth National Recreation Area are within the forest, although none of these areas are managed by Boise National Forest.