Mount Lyell divides the Tuolumne River watershed to the north, the Merced to the west, and the Rush Creek drainage in the Mono Lake Basin to the southeast.

The most common approach to Mount Lyell is from Tuolumne Meadows on a highly traveled section of the John Muir Trail.

The round trip is approximately 25 miles (40 km) and involves 4,500 feet (1,370 m) of elevation gain when starting from the Tuolumne Wilderness Office.

Seasonal and year-to-year variations on the glacier make it necessary to assess current conditions before choosing a route to the summit.

Low snow levels increases the grade to class 3 to 4 on the exposed granite ledges, in which cases it may be easier to ascend the glacier more directly to the summit.