How to Climb Half Dome with the Cables Down

Disclaimer:

• Don't do this.
• If you do this, don't rely on my advice. I'm a dumbass whose self preservation instincts can generously be called "lacking."
• If you rely on my advice, don't fall and die.
• If you fall and die, don't come back as a ghost and haunt me.

Okay, now let's talk about how to climb Half Dome.

Forcing yourself to smile is a good way to avoid having a panic attack.
Edit: A sharp-eyed reader pointed out that my waist strap was not doubled back, which is dangerous. Dumb mistake. Be smarter than me.

What is Half Dome

Half Dome is a smooth glacially-carved granite peak on the eastern end of Yosemite Valley. Its summit rises almost 5,000 feet from the valley floor and it is visible for miles around.

A snow covered Half Dome as seen from the center of the valley. The cables are hidden to the left of the vertical face.

Once described as "perfectly inaccessible" by Josiah Whitney, Half Dome is now climbed by thousands of people each year via a set of steel cables and wooden steps that are bolted into the east face. Due to the popularity of this hike, the National Park Service started requiring permits for the cables in 2011. These are available through a lottery and are limited to 300 people per day.

Hikers climbing the cables on the east face of Half Dome
Photo by Spencer Joplin

During the offseason (October 12-May 19), the steps and stanchions are taken down and the cables are left lying directly on the rock. After this date, no permits are required, but the park still allows hikers to climb to the summit at their own risk.

Half Dome cables lying on the rock
Photo via Outdoor Project

In case the warning at the top was not sufficient, you should know that in the 102 year lifetime of the cables, SEVEN PEOPLE HAVE DIED WHILE CLIMBING THEM. This is not a hike but an aided rock climb. The instructions below are my best attempt at keeping you safe if you choose, despite my warnings, to attempt this climb. This is compiled from a lengthy bit of searching for advice online as well as practical lessons learned while climbing Half Dome in October of this year.

Tying into the Cables

Each "cable" is not continuous but is instead a series of cable segments that overlap with each other. Additionally there are anchor points every 50-100 feet where the cable is bolted into the rock. This means that to safely climb the cables you will need to detach and reattach yourself from them several times on both the climb and the descent. For reasons that will soon become clear, I recommend using two lengths of rope, one connected to the cable via a Prusik knot as your primary tie-in and one connected via a carabiner as your secondary tie-in.

Alex at the base of the cables modeling the Prusik/carabiner combo that I recommend

Your attachment points need to satisfy these criteria:

Friction: If you fall, a carabiner will eventually stop you, but you might slide 50-100 feet along a 45 degree rock face before that happens. An ideal connection will provide friction if you begin to fall. This is where the Prusik knot comes in.

Reliability: Paracord and webbing ain't gonna cut it for this one. You need to tie in with something robust enough to stop your momentum if you fall to an anchor point.

Redundancy: The goal is to always be attached to the cable in at least one place. You will need at least two connections so that one can remain attached when you unclip from the end of each cable segment.

Quick and easy to connect/disconnect: You don't want to be on the cables for an hour each way.

Resistance to melting: This is why I recommend using a carabiner as your secondary tie-in. In a worst case scenario, your Prusik knot does not catch the cable immediately and instead runs along it for some distance. The friction from this could hypothetically melt your rope. Having a carabiner connected in parallel with your Prusik knot provides a backup.

So here is the plan: your primary connection to the cable should be a Prusik knot. This will be connected to the belay loop of your harness with a carabiner. Your backup is a separate length of rope with a carabiner clipped onto the cable. The carabiner rope will be tied into the belay loop of your harness. Below is a list of gear and instructions on how to execute this plan. [Edit 11/30/21: A much safer, but more time consuming method is to use two Prusik knots and a carabiner to attach to the rope. I opted for one of each.]

Gear you need (per person)

Harness (REI, $65): Any type of climbing harness will do. These are not typically rented by local outfitters for liability reasons. You're probably going to have to buy one or, if you're feeling thrifty and  are confident in your knot tying, make one out of rope.

Rope (REI, $90): Two lengths of 8mm rope cut to 6-8 foot (~2 meter) lengths, and tied into a loop using a double fisherman's knot. One of these will become your Prusik knot and the other will attach your carabiner to the cable.

Carabiners (REI, $20/ea): Two autolocking carabiners with wide enough openings for the cable (~0.75"/19mm). One of these will connect directly to the cable and the other will attached your Prusik knot to your harness.

[Edit 11/30/21] Screamer (Backcountry Gear, $20): I did not bring one of these, but it was an excellent suggestions from some feedback I received on this post. Add this between your rope and the carabiner that clips onto the cable. The screamer is able to absorb some of the dynamic load on the carabiner in the event that the Prusik slips/fails and you fall to an anchor.

GPS Beacon: Cell reception is unreliable in Yosemite. For safety, I recommend carrying an inReach Mini or a SPOT tracker, both of which have emergency distress beacons that will alert search and rescue. These can be rented from many outdoor sporting goods retailers. I've had good experiences with Outdoors Geek.

Shoes: Approach shoes, trail runners, or hiking boots are all viable as long as they have good grip. I used a pair of Hoka Speedgoats and their Vibram sole had no trouble sticking to the rock. Climbing shoes are unnecessary.

Water: Depending on your fitness level, you will be hiking for anywhere between 5 and 15 hours. Bring at least 500ml (16oz) of water per person per hour. A water filter is nice to have as a backup, but the water sources are sparse and unreliable near the summit.

Food: Eat early and often. You don't want to climb the cables while hangry.

Gloves (Home Depot, $20): While not entirely necessary, a good pair of gloves will save your hands as you pull yourself up the cables.

Warm Clothing: Mountain weather is unpredictable. Even on a "normal" day you might need to deal with a 30 degree temperature swing between the early morning and mid-afternoon. Warm layers, a rain shell, and a Mylar blanket/bivy are all good ideas.

Preparing for the climb

Fitness: Half Dome is a 16+ mile round trip. You will want to be in good cardio shape so that you are not depleted by the time you reach the base of the cables. You should also have enough upper body strength to comfortably pull yourself up the cables for anywhere between 10 and 30 minutes. Pull ups, rows, and deadlifts are good preparation for this part.

Gear: Practice tying and untying Prusik knots around something with a similar diameter to the cable (~0.75"/19mm). You will need to become proficient at doing this quickly and reliably. Remember that you will have to do this while out of breath on a rock wall.

Climbing the cables

Assess: The approach to the cables involves a very steep climb to the summit of the sub-dome on a set of granite stairs. While not technically demanding, this section is tiring. I recommend taking a lunch break on the sub-dome. This also provides a good opportunity to look for snow/ice/water along the route and to see if other groups are climbing ahead of you. Note: I strongly discourage anyone from attempting the cables in snowy or wet conditions, and you should absolutely turn around if you see any storm clouds moving in.

View of the cables from the sub-dome. Note the two climbers half way up.

Tie in: As you tie in at the bottom of the cables, slide the knot up and down the cable to get a feel for the amount of friction it provides. You can add/remove loops from the knot as needed to increase/decrease the amount of friction. When you're ready to climb, clip in with the carabiner.

Climb on: The initial climb is mild and can be done without relying too much on the rope. Higher sections will require you to hoist yourself up hand over hand. The cables are heavy and this is harder than it may sound. The Prusik knot should be pushed ahead of you with one hand to avoid leaving too much slack in the rope. The carabiner can be allowed to drag behind.

Switching cables: When you need to switch to a new section of cable, switch the carabiner first. This will provide a sturdy anchor point while you untie and re-tie the Prusik knot. This initial clip-in is also a good time to rest your arms and back. You can sit/stand and lean back with your ropes supporting you.

This is also a good time for pictures. Don't drop your phone though.

Don't panic: The cables can be dizzying when you're on them in person. If you feel overwhelmed, find a ledge or a good spot to clip in. Sit down and catch your breath. If this doesn't help, then it's best to descend.

Watch for other groups: I was fortunate enough to have the cables to myself. Passing another group is a potentially dangerous situation, which is probably best attempted at an anchor point.

Gear you do not need

Via ferrata kit: While tempting, a via ferrata kit will not provide adequate protection against a fall since carabiners do not have any friction in their connection to the cables. They will certainly prevent most fatal accidents, but it is also possible to injure yourself badly in a 50-100 foot fall from one anchor point to the next.

Webbing: This is a popular suggestion for climbers on a budget to replace their rope, but it is ill-advised. Similar to the via ferrata kit, a carabiner on a length of webbing will not provide any friction. Worse yet, webbing lacks the elasticity of a via ferrata kit and will be more likely to snap if it catches after a long slide down the rock. You would almost be better off with no protection than the false sense of security provided by this setup.

Helmet: Half Dome is a slab climb and, like most of Yosemite, the rock quality is amazing. There is very little chance of rock fall on the route and a helmet is just extra weight that would be better spent carrying extra food or water.

My Trip Report (10/28/21)

My wife Alex and I arrived in Yosemite on 10/25, just as a historic "atmospheric river" event dropped inches of rain and snow on the park. For our first three days in the park, we walked through 4-6" of snow on every hike and resigned ourselves to the fact that we would probably not get to summit Half Dome in those conditions.

Many inches of snow in the high country on 10/26

As the weather warmed up later in the week, we decided to at least hike to the base of Half Dome to see whether the cables looked feasible. On the morning of 10/28, we woke up at 4:30am after a luxurious night at the Awahnee Inn near the base of the peak. After a quick breakfast and a short drive to the Happy Isles parking lot, we were on the trail by 5:40, hiking by headlamp. We passed by Vernal Falls in the dark, stopping for a moment to put on our rain shells to avoid getting wet in the 35 degree weather. With the falls flowing at a rate usually reserved for the spring runoff, the Mist Trail was living up to its name.

Vernal Falls, illuminated by headlamp

The sun peaked out as we reached Nevada Falls, but it would still be a few hours before the temperatures warmed up. With the temperature inversion in the Merced River valley, we were very chilly walking through Little Yosemite Valley. Turning to climb up the John Muir Trail provided a welcome increase in body heat production.

At around 7,800' (1,000 feet below the summit) we got our first glimpse of the sub-dome and the cables and began to doubt whether we could even make it to the to the base of the cables. The sub-dome was covered in six inches of snow, and the granite stairway leading to its summit was completely invisible from our vantage point.

Our first view of Half Dome

We trudged onward and were happy to find enough footprints on the stairs that they were relatively easy to follow. We did end up taking a few detours around slick patches of snow but otherwise made it to the base of the cables without incident. From there, we could see two climbers slowly working their way up the route. There were two patches of snow above them, so we decided to have a snack break while we watched to see how they fared.

A pair of climbers on the cables

Seeing them top out gave us the confidence to attempt the cables, and we tied in and set to work climbing.

All smiles at the base

Alex went first so I could physically support her if she slipped or needed a rest. We reached the first anchor point and she quickly untied and re-tied her Prusik. I fumbled with my rope and ended up taking a bit longer. By the time I was reattached she was 20 feet ahead but starting to get nervous. I caught up and we regrouped at a small ledge. She was not feeling confident in her ability to pull herself along the full length of the cables, so we decided to descend back to the base and regroup.

After some discussion, we decided that I would try for the summit and she would stay on the sub-dome, where she could watch my progress. Feeling a bit guilty about leaving her but wanting to summit, I clipped back in and resumed my climb.

Back on the cables with Alex just barely visible on the summit of the sub-dome

The initial climb wasn't too strenuous and I made good progress, getting progressively better at tying my Prusik knot at each anchor. When I reached the segment of cable beneath the first snow patch, I realized that the melting snow was sending a steady trickle of water down the cable itself, making it that much more difficult to grip it. After a moment of contemplation, I decided to press on. The climb got more difficult from this point, as I was less willing to trust the friction of either my Prusik knot on the wet cable or my feet on the wet granite.

[Mom, if you're reading, this would be a good place to stop. I made it back down alive. The End!]

The scariest moment came just beneath the second snow patch. I unclipped my Prusik knot from my harness to untie it, and the momentary loss of friction allowed the knot to slide 20 feet down the cable and out of my reach. I hadn't considered this possibility. I was now attached with just my carabiner, at least 50 feet above the previous anchor, and I now had to descend a wet cable to retrieve my rope. I was successful in doing so, but this momentary lapse in concentration could have ended badly. I made a point of keeping a hand on the Prusik knot any time it was unclipped from my harness.

Heart attack-inducing moments aside, I made it to the summit and shared a gorgeous view of the valley with the other two climbers that we had watched earlier. We exchanged pictures and I texted Alex to let her know I was okay.

The iconic overlook at the summit of Half Dome. After climbing the cables, this doesn't seem scary.

The descent was substantially easier than the climb for two reasons: First, it was simply less physically strenuous going downhill in the thin mountain air. Second, descending allowed the Prusik knot to simply drag behind rather than constantly having to push it ahead. It pulled tight a few times and needed to occasionally be loosened, but this provided a welcome confirmation that had adequate friction to arrest a fall on a wet cable.

All smiles on the descent

I reached the bottom of the cables about an hour after I had started the climb up them. Accounting for 20 minutes of photo taking at the summit, that means my moving time was 40 minutes to the summit and back, which is certainly not fast but might provide a good benchmark for similarly fit hikers who attempt this route.

With plenty of daylight left, we took a leisurely stroll back to the trail head, stopping to take pictures of Nevada Falls from the gorgeous viewpoints on the JMT.

Right to left: Nevada Falls, Liberty Cap, and the backside of Half Dome

Our car-to-car time for the whole hike was a little under 10 hours, with most of that being moving time. Hikers who are better acclimatized to altitude will probably be able to go faster, but we found that this speed was a nice compromise between finishing quickly and being able to take in the sights along the way.

Further Reading

Yosemite.ca Forum: Lengthy and informative discussion about climbing Half Dome with the cables down.

Summitpost.org: Another good discussion. Pay particular attention to the recommendation not to climb the cables while they're down.

How to Tie a Prusik Knot: Short video produced by REI. Good as a reminder the night before your attempt.

Outdoor Project - Climbing Half Dome in the Shoulder Season: A similar article to this one, although they recommend two Prusik knots.

Alltrails - Half Dome via the JMT: A map of the route which can be downloaded to your phone for offline navigation.

My GPS Track on Strava: Self explanatory.