Moulins are drainage holes formed by meltwater boring through the ice. As water cuts through the glacier, it creates vertical shafts and horizontal tunnels, many of which plunge deep beneath the ice. Few reach the immense size of the moulin before us. We stood at the edge, peering into an irregular, narrow opening carved into the glacier’s surface.

Its full depth was hidden from sight. Meltwater had sculpted the glacier’s upper layers around us into overhangs, some projecting above our heads and others hanging beyond the rim, while large chunks jutted precariously beyond the open shaft below. Together, these details clarified the moulin’s vertical drop and the precariousness of our vantage point.

We geared up in full rain gear and put headlights on our helmets. Once ready, we set up a rappel system. I had not rappelled in years, so starting on a sharp overhang with gear all over me was not ideal. My knees shook as I stood at the top, trying to figure out how to get over the razor edge that led into an extreme overhang.

Those initial moments at the edge lingered with me. After about 5 minutes of floundering at the top, and with considerable prodding from Quinn, I finally committed and went over the edge, unsure what to expect. That leap was definitely the hardest part. As I descended past the first 15 feet, the cavern opened around me into a large space, which we estimated to be about 30 feet wide.

When people try to describe what it’s like to be in a large moulin like this, a common theme is that it feels like being in a sensory deprivation tank. You are suddenly very aware of the fact that you feel you aren’t supposed to be in this space. There are so many ways you could end up dead, and only one way out. However, as I descended into this breathtaking open space, my inclinations started to shift.

The sunlight beamed down into one side of the cavern, and a massive torrent of water pounded its way onto the ice below me. I wasn’t really thinking about the dangers anymore. Lowering down, I could see a small shelf of ice where Adam had set up an anchor for us to clip into. I got off the belay so Quinn could follow us down into the chasm. After we had all made our way down, we took a minute to explore and take it all in. As moulins go, this was certainly the biggest and most intimidating I’ve ever seen.

The three of us ended up spending almost three hours in this hole. Because water had melted the hole above us in a unique way, only Adam could climb out. He has multitudes more experience than Quinn or me. Instead, we opted to ascend the rope up about 20ft, where Adam would then lead climb out and place protection for Quinn and me.

Anchoring on glaciers should involve two independent anchors to ensure safety, such as two ice screws on bare ice. In our situation, we were all connected to a single anchor on a vertical wall of ice right above the deep moulin, leaving us with very little space as gravity pushed the people on the edges toward the person in the middle. It was here that we made our escape plan.

I managed the 70-meter rope in my pack. Simultaneously, Quinn would belay Adam with it as Adam led the climb all the way up and out. As Adam took the first few swings at the bulletproof ice that hung above us, I became aware that for the next few minutes, we were incredibly exposed if he were to fall.

Fortunately, Adam is an extremely skilled ice climber. In the end, I tried to climb out, but my arms were exhausted before I began. Adam had to support me so I could get out. Meanwhile, Quinn climbed the rope and removed the screws Adam had placed.

Glacier moulins can pose abrupt, significant challenges to mountaineers. When all three of us finally made it out, exhausted, muddy, and cold, we felt absolutely elated about the experience. I kept thinking about what Adam had said that day. And I lingered on his observations; few people in the world have the resources, knowledge, or even the possibility to do something like what we just did.