Matthew Ward from Idaho and I made an attempt in July on a gray flow of ice toward the left end of the large, quasi-vertical rock barrier that characterizes the west face of Sajama (6,542m), Bolivia's highest mountain. We bailed on this super-impressive route because the ice was too poorly formed.

With Matthew back home and the weather forecast better for the Cordillera Occidental than the Real— like so many times during 2018—I decided to have another try, solo. I took a bus to the start of the approach and then carried a heavy sack up to the standard base camp (4,800m), where I set up my tent in a fierce snowstorm. Next day there were 90km/hour winds, the sort of winds for which Sajama is well known. Fortunately, early the following day, August 6, the weather was near perfect, with no wind and a million stars in a clear night sky.

I headed up the initial slopes toward the west face, but this time opted for a line of black ice farther left than the one Matthew and I had eyed, close to the large icefall in a corner at the left end of the wall. (This broad icefall may have been climbed in the past, but no details are available.) The black and brown ice was very tough; I've not seen a stranger frozen waterfall. It was a little over 100m in height: 70m were vertical, and 20m of this was on thin ice, about 3cm thick and delicate to handle. This section I felt to be WI5+, and I took an hour to climb just a few meters—my forearms were as pumped as after a hard sport route.

Above, I continued via a system of gullies, mostly easy but beautiful and logical. These often ended in short (3m to 6m) vertical barriers of blue and white water ice. There was time to recover while climbing the easy sections in between, but I've never been so tired after an ice climb.

I emerged onto the northwest ridge, Sajama’s normal route, and followed this to the summit, arriving at 6 p.m., 13 hours after setting out from base camp. Seventy-three years to the day before my climb, the first atomic bomb in the history of warfare was dropped on Hiroshima, Japan. Because of this I chose to name my route Days to Remember (WI5+ M4). I had covered 1,750m from base camp to summit, and now, without bivouac gear, I needed to get down.

While the normal route is easy, the route-finding in parts is certainly not easy in the dark. Below high camp (ca 5,650m) the volcanic terrain is not "sympathetic," and many of my past clients have expressed the view that this section is harder than summit day. I was back in base camp at 10 p.m.

This is the hardest route to date on Bolivia's highest peak, but I think it is only a question of time before the young climbers of La Paz repeat it.

– Robert Rauch, Bolivia Tours, rauchrobert@hotmail.com