Thousand Lakes Wilderness, US Wilderness Area in Shasta County, California

Thousand Lakes Wilderness is a protected area in Lassen National Forest, California, featuring volcanic terrain with seven major lakes scattered throughout. The landscape includes steep hillsides, coniferous forests, and mountain ridges shaped by ancient glaciation.

Congress protected this land in 1964 through the Wilderness Act to safeguard its geological and natural features. The terrain formed over millions of years through volcanic activity and was later shaped dramatically by ice-age glaciers.

The name is a misnomer: about seven major lakes lie within the wilderness, not a thousand. The largest, Eiler Lake, honours Lu Eiler, credited with discovering Thousand Lakes Valley. All the larger lakes hold trout, and the surrounding forest shelters black-tailed deer, black bear, pika, pine marten, spotted owl and Clark's nutcracker, with elk visiting occasionally.

Four trailheads give access to about 21 miles (34 km) of trails within the 16,335-acre wilderness. The lowest ground, 5,546 feet, lies at the base of Crater Peak, and the high country holds snow into early summer. Carry water treatment for the lakes and allow for the climb between trailheads and the lake basins.

Crater Peak, the tallest summit in Lassen National Forest, rises from the wilderness and bears clear marks of ancient glacial erosion. This peak was once part of the original Thousand Lakes Volcano before ice-age processes wore down its top.