[1][2] The Wehana–Tucannon Wilderness consists primarily of rugged basaltic ridges separated by deep canyons with steep slopes.

Above about 4,500 feet (1,400 m), it transitions to a forest of lodgepole pine with some species of larch, fir, and spruce as well.

[1][3] The Wenaha–Tucannon Wilderness is home to a variety of wildlife, including Shiras moose,[4] Rocky Mountain elk, bighorn sheep, whitetail and mule deer, black bear, cougar, grey wolf,[5] coyote, snowshoe hare, rattlesnake, and pine marten.

Both the Tucannon and Wenaha Rivers provide spawning habitat for Chinook salmon and steelhead trout.

[1][3] Popular recreational activities in the Wenaha–Tucannon Wilderness include camping, horseback riding, wildlife watching, and hiking the area's 200 miles (320 km) of trails.