Wonder Mountain Wilderness is a designated wilderness area encompassing Wonder Mountain in the Olympic National Forest on the Olympic Peninsula of Washington in the United States. The wilderness comprises 2,349 acres (951 ha) bordering Olympic National Park and administered by the U.S. Forest Service.
Wonder Mountain Wilderness is roughly triangle-shaped. A high ridge encompasses the southern point of the triangle, rising to the peak of 4,848-foot (1,478 m) Wonder Mountain. Below the summit stands a heavy forest of western hemlock, Douglas fir, and silver fir. Alder, willow, and vine maple grow along McKay Creek and Five Stream, both of which have their headwaters in the wilderness. huckleberry and thimbleberry are also common.