Distance: From 1.4 miles (2.2 km) to 24 miles (38 km) round trip
Trailhead Elevation: 8,600 feet (2,620 meters)
Elevation Gain: Less than 100 feet (30 meters) for the first 8 miles (13 km); 2,500 feet (760 meters) if you actually go all the way to Donohue Pass
The Big Blue "P" is the trailhead parking lot. Watch for the "Dog Lake" signs, but don't get confused and park in the Dog Lake lot on Tioga Road itself - you want the one on the drive that leads to the Tuolumne Meadows Lodge. This lot is a hundred meters or so west of the actual trailhead, which is at the southwest corner of the parking lot for the lodge.
The big red bed, partially obscured by the giant green hikers, is the site of the lodge itself. You can get snacks and use the bathroom here.
The giant green hikers, as you already know if you've looked at any of the other trail maps, mark the trailhead location.
The balloons mark possible turnaround points. From left to right:
The green balloon marks one of the trail's most picturesque spots, where a pair of bridges span the Tuolumne River, with a meadow upstream and an eastward view of the less famous side of Mammoth Peak. It's about three quarters of a mile from the trailhead.
The blue balloon marks another pretty bridge, this one over Rafferty Creek. It's about a mile and a half hike from the trailhead to this spot.
The pink balloon shows the location of a large meadow, with the Tuolumne flowing through the opposite end. It's about two miles from the trailhead.
The yellow balloon, about three miles from the trailhead, is the location of another meadow, again with the Tuolumne flowing through it. It's actually the beginning of a series of meadows that lasts for several miles. Find the same yellow balloon on the satellite view to get a better idea.
The red line marks the trail. I've traced it out to the park's boundary at Donohue Pass, 12 miles from the trailhead, but since this is part of the Pacific Crest Trail, it continues south to somewhere near the Mexican border.
It's worth zooming out (click on the '-' button on the map) to see what a natural spot Lyell Canyon is for a trail. There are very few places in Yosemite where a trail can go more than eight miles with essentially no elevation gain at all. If you're interested in the Mono Pass trail, you can find it running roughly parallel to this one, one canyon over to the east.