Hike to the top of Half Dome

What it's like

Half Dome rises nearly 5,000 feet (about 1,500 metres) above the floor of Yosemite Valley, to 8,800 feet (about 2,680 metres) above sea level. The day hike is 14 to 16 miles (23 to 26 km) there and back with about 4,800 feet (1,460 metres) of climbing, and the National Park Service says most hikers take 10 to 12 hours, some longer.

Most people start at Happy Isles (shuttle stop 16) and share the first part of the way with the Vernal and Nevada Falls trail, then continue past Little Yosemite Valley. The summit is typically 15 to 20°F (8 to 11°C) cooler than the valley, and wind is common.

The cables

Two metal cables let hikers climb the last 400 feet (about 120 metres) of bare granite without climbing equipment. They are usually put up on the Friday before Memorial Day and taken down the day after the second Monday in October, but the dates can change with conditions.

The park says relatively few people have fallen and died on the cables since 1919, and that nearly all fatal falls happened when the rock was wet. Do not start up the cables if there are storm clouds about or the rock is wet. Be patient with slower hikers, let faster ones pass where you can, and stay on the inside of the cables. Sturdy gloves with a good grip help; pack them out afterwards.

Getting a permit

A permit is needed every day the cables are up, for anyone going beyond the base of the subdome, where rangers check them. The park allows up to 300 people a day, about 225 day hikers and 75 backpackers (who get theirs with a wilderness permit). Bring photo ID and the email confirming the permit is paid. Permits cannot be passed to someone else.

What to carry

• Well broken-in boots with good ankle support and grip. Blisters and ankle injuries are among the most common injuries on the trail.
• Water. The park says carry at least 1 quart (1 litre) to the top of Vernal Fall, 2 quarts (2 litres) to the top of Nevada Fall and 1 gallon (4 litres) to the top of Half Dome. The only treated water is a summer drinking fountain at the Vernal Fall footbridge; river water must be boiled, treated or filtered.
• Salty snacks, to go with the water.
• A headlamp or torch with spare batteries. The park is plain that a phone does not count, and many hikers struggle coming down in the dark without one.
• A map and compass, and the skill to use them.
• {"Keep food within arm's reach or on your back": 'bears are common and will take packs.'}

Timing and turning back

Leave around sunrise or earlier and set a firm turnaround time; the park's own example is 3.30 pm, after which you turn back whether you have reached the top or not. Thunderstorms are more common in the afternoon, and the summit is a dangerous place in a lightning storm, so if one is near, do not go on; if you are on top, leave.

The park also warns of heat exhaustion, dehydration and hyponatremia (low blood sodium), and of altitude sickness. A severe headache with nausea is a reason to go down.