Boulder River Wilderness is made up of dense forests and steep ridges that rise to the summits of Three Fingers and Whitehorse Mountain.

The Long Creek Research Natural Area on the south slope of Wiley Ridge is also protected within the wilderness boundary.

[3] Black bears, black-tailed deer, and elk inhabit the forest, and mountain goats can be found on the rocky shelves above the tree line.

[2] Boulder River Wilderness boasts approximately 25 miles (40 km) of trails, though the central core of the area remains rough and trailless.

Another trail crosses the northeast corner of the Wilderness over Squire Creek Pass, with outstanding views of the high crest.