The Deadliest Mountains

Everest is the famous one, the tall one, the one with the queues. It is not the dangerous one. Across 76,519 climber records in the Himalayan Database, Annapurna I kills 4.3 percent of the people who go up it. Everest kills 1.4. The peaks that frighten the people who actually climb them are rarely the peaks that frighten everyone else.

That picture is the whole article. Eight giants, all within about ten percent of each other in height, drawn honestly from sea level so none of them towers over the rest. Height cannot tell them apart, so I threw height away as the signal and colored each summit by how often it kills. The red ones are the killers. Notice they are not the tall ones.

A short climb of the same ridge, if your reader wants the terrain to assemble itself:

Why a mountain chart has to start at sea level

There is a tempting version of this chart that crops the y-axis to start at 8000 metres. It looks dramatic. It is also a lie. The tallest of these peaks, Everest at 8850 metres, is only 1.09 times the height of the shortest in the group, Annapurna I at 8091. Baseline the chart at 8000 and Everest suddenly looks five or six times taller than a peak it beats by nine percent. The silhouette would be carrying a ratio the data does not contain.

So the baseline sits at zero. Every summit is a thin band near the top of the frame, because that is what these mountains actually are: heights that barely differ, packed into the last tenth of the climb. When the thing you want to show does not vary, stop encoding it as size. Color carried the death rate instead, and the chart stopped lying.

The killers

Rank the peaks by death rate and the order has nothing to do with fame.

• Annapurna I: 4.3 percent
• Kangchenjunga: 3.7 percent
• Dhaulagiri I: 3.3 percent
• Everest: 1.4 percent

I restricted this to peaks with at least 400 recorded climbers, because death rate is a ratio and ratios go haywire on small samples. One fatal accident on a peak climbed twice reads as a fifty percent death rate, which tells you nothing. With that floor in place, Annapurna I sits at the top with 72 deaths across 1,669 attempts. Everest, for all its 21,813 climbers and 306 deaths, lands seventh. The mountain that gets the documentaries is roughly three times safer than the one that does not.

What makes Annapurna worse is not height. It is the terrain above the climbers. Annapurna’s normal routes run under enormous hanging seracs and avalanche-loaded faces, and a wall of ice does not care how strong you are. Everest’s standard routes are murderously high but comparatively predictable. Fame tracks height. Death tracks what is overhead.

The oxygen line

Now the cleanest natural experiment in the dataset. On Everest, some climbers use supplemental oxygen and some refuse it, and the database records which. So I split Everest by that one choice and left everything else, the mountain, the altitude, the route, held fixed.

Without bottled oxygen, 1.96 percent of Everest climbers died, across 9,187 records. With it, 1.00 percent died, across 12,626. The gas roughly halves your odds of dying on the mountain. This is not a randomized trial, and the people who skip oxygen are a self-selected, often more extreme group, so the true causal effect is tangled with who chooses what. But the raw gap is a factor of two on a sample of more than twenty thousand people, on one mountain. The body above 8000 metres is slowly suffocating, and a tank of oxygen is the only thing that argues with the altitude.

The mountains got safer

The last finding is the hopeful one. Bin every climber by the decade of their attempt and the death rate falls off a cliff.

The 1970s were the worst decade in the record, with 4.2 percent of climbers dying. The 2010s came in at 0.9 percent. That is a 4.7 times drop. Better weather forecasting, fixed ropes, satellite communication, helicopter rescue, and decades of accumulated route knowledge all bent the curve down. The mountains did not get lower. The people climbing them got better at not dying on them.

None of this makes the high peaks safe. A 0.9 percent chance of death is still about one in a hundred, which is a number no other recreation would tolerate. But the trend is real and it is steep, and it runs against the easy story that Everest has become a careless tourist trap. The data says the opposite. Every decade, the same mountains have let fewer people die.