Last week, two climbers at the Denali 14.2 camp, as reported in Denali Dispatches from the NPS, came very close to expiring from carbon monoxide poisoning. While cooking in their inadequately ventilated tent, one climber started feeling funny and went out to shovel snow. On his return he found his seizing partner and yelled for help. Rangers, fortunately close by, quickly treated with oxygen and both climbers were evacuated. Feeling funny and a bit sick never came at a better time for them.

There are the obvious physical dangers climbing Denali: the wild weather from above, the obvious crevasses and avalanches on the ground and the simple knowledge you shouldn’t fall off on some of the deceptively steep sections.

Heading down the summit ridge, 11 p.m. and a long ways to go back to 14.2 Camp.  Photo: R. Anderson

Yet so many times it seems what you can’t see on a mountain can pose the real danger – and perhaps more than on most peaks, that is the case with Denali.

On Denali, the often heavy snowfall quickly seals you inside your tent and encases the snow flaps – and getting out to dig it out is less than fun, if still rather important. By late in the season, the deep holes from previous tents provide welcome shelter but also mean you are half under the snow before you even put the tent up. Oh for the App that measures carbon monoxide. And while the simple rule that, ‘if the stove is on, the vents are open,’ in a howling blizzard after a long day at altitude, keeping the spin drift at bay may seem a higher priority.

One of the reasons the guided groups on Everest are statistically safer is not only because a guide has safety as his first priority, but also because years of climbing has given them the intuition and 6th sense to feel when things aren’t right. Over on Denali, crevasse after hidden crevasse must be crossed, marked by the subtlest of shading and slope. Yet only one who has listened to skis on snow on a glacier again and again can use this sense to ‘hear’ the crevasse whispering beneath them as the sound of ski on snow changes.  Seeing and sensing the unseen becomes a mix of all the senses and just a bit of luck.

With the unseen winds and storms, no matter how good the forecasts, weather can still be divided into probabilities of thirds. 1/3 for the big picture satellite and wind maps, 1/3 for the detailed, elevation specific weather forecast, and 1/3 you look up at the sky, sniff the wind, read the clouds and go or not go higher.

As much as the old abage, ‘what you can’t see won’t kill you’ is very untrue.   On Denali the unseen is perhaps the most dangerous. With the mix of carbon monoxide in the tent, and hidden crevasses outside the tent, experience and intuition for the unseen and unexpected would seem to be the best skill to have honed.