The Hetch Hetchy to Lake Vernon Trail in Yosemite starts from the parking lot close to the O'Shaughnessy Dam at the Hetch Hetchy Reservoir, and goes to Lake Vernon through the Yosemite Wilderness.
Another option is do the 14-mile hike around Hetch Hetchy Reservoir. This hike starts along the north rim of the reservoir, past two waterfalls. About four miles in, the trail cut...