Thornton Lake Trail

This trail doesn't ease you in. The first couple of miles climb relentlessly through dense old-growth forest on a rough, root-laced path that was originally a logging road — expect uneven footing and sections where you're essentially scrambling over deadfall. Around the halfway point, the forest thins and you'll catch your first glimpses of Trappers Peak before the trail drops steeply toward Lower Thornton Lake, nestled in a glacially carved basin surrounded by jagged peaks. The lake itself is a deep, impossibly clear alpine gem backed by the remnants of a small glacier. The total elevation gain is roughly equivalent to climbing a 200-story building, with a cruel twist: the trail drops about 500 feet to reach the lake, meaning you'll pay for that descent on the way back when your legs are already spent. This one rewards hikers who treat difficulty as the price of admission for genuine North Cascades solitude.