The 500,000 acre North Cascade National Park consists of the most rugged, glaciated peaks of the Cascade Range. There are roughly 400 miles of hiking trails through old growth red cedar and hardwood forests. On the eastern edge of Ross Lake, the route up Desolation Peak has 4500 feet of vertical and provides beauty and solitude in sub-alpine meadows.
Also, check out Cascade Pass, Copper Mt. Trail, and Chilliwack Trail
Overall, Southern Trails is the 3rd most popular hiking trail of all 56 hikes in Washington.