There are two hike options for folks heading to Three Corner Rock. A shorter option is available, at just 4.4 miles round trip with 800 feet of elevation gain. Start where the Pacific Crest Trail crosses Road CG 2090. Selective logging occurred on both sides of the trail within the last five years. The well-graded trail gains elevation, passing into mountain hemlock and Pacific silver fir forest. Views open up as the trail climbs the ridge in three switchbacks. Mount Adams dominates the northeast horizon. As the path curves around the ridge, Mount Rainier and Mount St. Helens come into view.
After 1.5 miles, large fallen signs mark the junction for the Three Corner Rock Trail. Turn right and follow the trail through open woodland and beargrass openings. Pass a short, marked side trail, signed "Water Trough" that leads to a piped spring. Shortly beyond, the trail ends at a jeep road. Turn right and climb the badly eroded tread a few hundred yards to a 4-way junction at a saddle. To the left is a gravel road accessing a microwave relay tower. Straight ahead is the Three Corner Rock Trail climbing 9.2 miles from the Stebbins Creek trailhead along the Washougal River. To the right is the rock pinnacle itself.
Walk up the spur jeep road to the base of Three Corner Rock. Concrete steps lead to within 12 feet of the top. Scramble the rest of the way to the flattened top where a lookout tower formerly stood. Enjoy 360 degree views that include Mounts Hood and Jefferson to the south, Mount St Helens and Mount Rainier to the north, Mount Adams to the northeast, and the Columbia River glinting to the southeast and southwest. Other notable high points include Silver Star, the highlands of Indian Heaven Wilderness, and the Columbia River Gorge sentinel peaks of Dog Mountain on the Washington side and Mount Defiance on the Oregon side.
If you'd like, it's possible to do a longer route of nine miles round trip with 1,900 feet of elevation gain. Start where the Pacific Crest Trail crosses Road CG 2000. The PCT starts in a former clearcut, then traverses second-growth Douglas-fir forest, winding in and out of several creek drainages before finally reaching the ridge leading to Three Corner Rock.