One of the most strenuous trails in North Cascades National Park reaps stunning rewards for those willing and able to make the grueling trek. The historic lookout on the summit of Washington’s Sourdough Mountain can be approached via Diablo or Pierce Mountain sides. Both trails are steep, and both pass through forest and meadow communities before arriving at the rocky lookout site with views of lakes, peaks and glaciers in every direction. Pictured here is the view never the top of Sourdough Mountain with Diablo Lake visible down below. Photo by Chris Holm, National Park Service.