Physiographically, the Klamath Mountains include the
Siskiyou Mountains, the
Marble Mountains, the
Scott Mountains, the
Trinity Mountains, the
Trinity Alps, the
Salmon Mountains, and the northern Yolla-Bolly Mountains.
 They are a section of the larger Pacific Border province, which in turn is part of the
Pacific Mountain System (Pacific Coast Ranges) physiographic division.
The three highest peaks in the Klamaths are
Mount Eddy in
Siskiyou County, California, at 9,025 feet (2,751 m), and
Thompson Peak and Mount Hilton in
Trinity County, California, at 9,001 feet (2,744 m) and 8,934 feet (2,723 m), respectively. The northernmost and largest sub-range of the Klamath Mountains are the
A large portion of the Klamath Mountains is managed by the
United States Forest Service. Several
national forests lie in the Klamath Mountains region, including the
Shasta-Trinity National Forest,
Siskiyou National Forest,
Klamath National Forest,
Six Rivers National Forest, and
Mendocino National Forest.
The Klamath Mountains contain 11
wilderness areas in both Oregon and California: