The wilderness comprises 2,349 acres (951 ha) bordering Olympic National Park and administered by the U.S. Forest Service.

A high ridge encompasses the southern point of the triangle, rising to the peak of 4,848-foot (1,478 m) Wonder Mountain.

Alder, willow, and vine maple grow along McKay Creek and Five Stream, both of which have their headwaters in the wilderness.

Two forest roads that run near the southeast and southwest borders are closed to motor vehicles from October to May to provide protection for wildlife.

The southeast road has been permanently closed at the lake Cushman bridge for years about ten miles from the base of wonder mountain.