Is the Lyell Canyon trailhead about 22 or 33 miles from Happy Isles? My map doesn't show the trailhead. Is it right near the backpackers' campground at Tuolomne, or further away?
From the Tuolumne Meadows Ranger Station to Happy Isles on the Yosemite Valley floor is approximately 25.5 miles. I did this hike about 3 years ago. My 2c.