About This Route
The Four Mile Trail climbs 4.8 miles (9.6 roundtrip) from Yosemite Valley's Southside Drive to Glacier Point, gaining 3,200 feet with panoramic Half Dome views. Trail runners tackle it for vert training; shuttle back via NPS bus. NPS emphasizes its steepness; not for speed demons without prep.
Safety Considerations
Steep drop-offs lack railings; one misstep fatal. Heat exhaustion common on unshaded south-facing slope; run early. Rockfall from Union Point; wear helmet. Thunderstorms strand above treeline; NPS advises noon summit cutoffs. Fall creek high water; pole-assisted crossings. Bears less issue but secure gels.
Essential Gear
Hoka Speedgoat shoes, Gregory Nano 18 pack, Suunto 9 Peak watch, Petzl Reactik headlamp, climbing helmet, Leki Micro poles, Tailwind nutrition, space blanket.
Emergency Tips
Injured? Stay put, signal downhill with mirror/whistle. Glacier Point ranger station nearby; 209-372-0297. Descend slowly if able.