Sierra scenery without Sierra traffic is the lure of this 18-mile loop. Starting beneath Douglas fir and big-leaf maple on the Canyon Creek Trail, you'll climb into the very alpine Sky High Lakes Basin. Views expand as you approach the PCT junction, situated 7 miles from the trailhead on a ridgetop at 6,400 feet. Hike the PCT northbound, then turn northwest on the Marble Rim Trail, ascending an open ridge of light-colored marble for less than a mile. A short off-trail section brings you to Marble Mountain's 6,880-foot summit and exquisite views south from 1,000-foot cliffs to the Trinity Alps and north to the dark hulk of Black Mountain. Backtrack to the PCT and hike south 1.4 miles to the Shadow Lake Trail and the hike's most spectacular campsite--perched at cliff's edge hundreds of feet above Sky High Lakes Basin. Then it's just .3 mile south on the PCT to a left turn down Red Rock Valley to the trailhead.