The only one of California's 18 national Forests not crossed by a paved road or highway, the Mendocino National Forest is especially attractive to people seeking an outdoor experience of tranquility and solitude. It is comprised of 913,306 acres and is approximately 65 miles long and 35 miles wide. The Berryessa Snow Mountain National Monument was established in 2015 and lies on the southern part of the forest.

Elevations in the Forest range from 750 feet in the Grindstone Creek Canyon in the Sacramento Valley foothills on the Forest's eastern edge to the 8,092 feet of South Yolla Bolly Mountain in the northern part of the Forest. The average elevation is about 4,000 feet.