Sanhedrin Wilderness is a protected backcountry area in Mendocino National Forest on Northern California’s North Coast. Established as wilderness in 2006, it spans 10,666 acres and remains notably undeveloped, with no managed trails and only limited public access at Big Signal Peak. Older roads and cattle paths still cross parts of the land from before its designation. The wilderness is valued for its rugged character, unusual blue-green and red serpentinite soils, and an unstable fault in its southern section. It also provides habitat for rare and sensitive species, including the Anthony Peak lupine, northern spotted owls, and threatened steelhead in Whitney and Thomas creeks. In 2022, another 917 acres near Thomas Creek were added.