Ape Canyon is one of the most rewarding hikes on the south side of Mount St. Helens, offering a steady climb from deep forest into wide-open volcanic terrain with expansive views of Mount St. Helens, Mount Adams, and Mount Rainier. This out-and-back route is about 11 miles roundtrip with roughly 1,400 feet of elevation gain, making it a strong choice for hikers looking for a fuller day on the mountain without committing to a summit climb.

The trail begins near Lava Canyon and follows the edge of the Muddy River lahar zone before climbing through one of the remaining old-growth forest stands on Mount St. Helens. As you gain elevation, the dense forest gives way to open slopes, light-colored cinders, summer wildflowers, and increasingly dramatic volcanic views. Near the upper end of the hike, the landscape opens onto a broad plain and the route reaches the edge of the canyon itself before continuing toward the Loowit Trail.

What makes Ape Canyon especially memorable is the contrast. You begin in shaded evergreens and finish in a stark, beautiful volcanic landscape that feels almost otherworldly. It is one of those Mount St. Helens hikes that gives visitors a strong sense of both the mountain’s surviving forest and the raw terrain shaped by eruption and mudflow. The trail is also popular with mountain bikers, so hikers should stay aware and share the trail carefully.

For planning purposes, the trailhead sits near Cougar, Washington, at approximately 46.165526, -122.09105. Parking is limited, with space for about seven vehicles at the trailhead, and overflow parking may be available nearby at Lava Canyon or Lahar Viewpoint. A Digital Day Pass, Northwest Forest Pass, Interagency Pass, or the posted day-use fee is required. Potable water is not available at the trailhead.

Getting there: From Cougar, take Lewis River Road east as it becomes Forest Road 90, then turn left onto Forest Road 83 and continue about 8.4 miles to the Ape Canyon Trailhead near the end of the road. Forest Road 83 is paved, but the Forest Service notes that it can be rough, so drive with caution.

Call to action: Add Ape Canyon to your Visit Mt. St. Helens itinerary for a hike that delivers old-growth forest, volcanic scenery, and some of the most impressive south-side views in the monument.

Current seasonal note: The Forest Service currently lists the Ape Canyon trailhead as closed for winter. As of April 1, 2026, Forest Road 83 is gated at Marble Mountain Sno-Park due to snow, so the trail cannot currently be accessed by vehicle. The listed main season of use is June through October.