Olallie State Park is a 2,500- acre day use park on the western slopes of the Cascade Mountains featuring dramatic waterfalls, cliff formations and old-growth trees over 10 feet in diameter. The park is a popular location for hiking, picnicking, fishing and rock climbing. The park's popular hiking destinations include Twin Falls, Weeks Falls, Cedar Butte and Mount Washington
.A one-mile hike off exit 34 leads visitors to two spectacular waterfalls, including the 100-foot cascading Twin falls. Old-growth trees 12 to 14 feet in diameter add color to the park.The area abounds in huckleberries.
The rock-climbing area is adjacent to the park, above the Iron HorseTrail. Rock-climbing equipment is necessary.Olallie provides access to the Iron Horse Trail, an old Milwaukee Railroad path that starts in North Bend
and extends to the Idaho border. The Iron Horse Trail permits mountain biking and horseback riding. The river is open for fishing. Check local regulations.