The prominent spires in the southeast that make up the Castle Crags are the main attraction and are similar to the granitic rock landscape in parts of Yosemite National Park.

In the northern portion of the wilderness, the landscape is more like the Klamath Mountains with glacial erosion, several cirques, and abundant rainfall with a high, east-trending divide.

)[3] There are mineral springs at the base of the crags which were used by the early fur traders, and after the Southern Pacific Railroad was completed into the area, health resorts sprang up as well.

Forested areas have incense cedar, white fir, ponderosa pine, several types of oaks with Pacific dogwood and maple in riparian zones.

The Forest Service encourages the use of Leave No Trace principles of outdoor travel to minimize impact to the environment.