The Hetch Hetchy to Lake Vernon Trail is a backcountry route in Yosemite National Park that starts near O'Shaughnessy Dam on Hetch Hetchy Reservoir and continues through the Yosemite Wilderness to Lake Vernon. Covering 23 miles round trip, or 11.5 miles each way, it is a substantial wilderness hike rather than a short walk along the reservoir. The route gains about 2,700 feet in elevation overall, with a reported climbing total of 4,707 feet over the full out-and-back journey. Overnight travel on the trail requires a wilderness permit available through the Hetch Hetchy ranger station or online reservation.