Mount Thielsen

June 27, 2024

2799m

Diamond Lake, OR

Mt. Thielsen is one of the volcanoes in central Oregon with an extremely iconic profile. The climb is not as hard as it appears, but the summit tower still requires some mandatory 4th class climbing but the rock is decently good. This is such a classic that a lot of folks had come from very far away to do the climb, or at least are aware of it. This was the second volcano that Erica and I did in our Oregon trip. On the first day we climbed Broken Top and then drove down to Diamond Lake for camping. The official campground was very packed but we were lucky enough to find a spot next to the lake. We watched an amazing sunset and cooked our own dinner, and the next morning we woke up at 6 am to prepare for the climb. The drive to the trail-head took only 10 minutes from where we camped.

Erica and I eventually found a campsite next to the lake

We then watched a gorgeous sunset over Diamond Lake

Mt. Thielsen via the standard route. GPX DL

It was funny that I discovered Thomas Morrissey did this peak the day before, so I messaged him at the very last minute for some beta, and the response was to not carry crampons nor an ice axe, so it would be trail-runners from the trail-head to the summit. This was a great news as we were both tired from the all-nighter drive and the long day on Broken Top. I opted to wear the Arc’teryx trail shoes this time and they of course did not let me down. There wasn’t much worth noting about the approach other than it was a bit boring. We encountered patches of snow near treeline but those were either avoidable or flat enough to walk on without donning traction. The condition was also very soft despite the cooler overnight temperatures. There was a group-of-three from Ohio that started about half an hour earlier but we caught up and passed them somewhere around that chossy scrambling section on the upper west ridge. We were not far below the summit tower but the terrain forced us to do some route-finding. I led us traversing climber’s right onto the next rib and then merged back to the main path. There was some compact choss to content with, unfortunately. It was then mostly an easy plod to the base of the climb except for the final 10 m or so that had some 3rd class scrambling on ledges.

There were some deadfalls on the lower sections of this trail

Erica with our first close-up view of Mt. Thielsen

Diamond Lake with Mt. Bailey. We camped at the shore the night before

Dutton Ridge and Applegate Peak on the south rim of Crater Lake

Erica plodding up the increasingly loose terrain

As you can see Erica had put her jacket on. It was quite windy here

At the summit block we ascended climber’s right side of it

The climb did appear rather straightforward but we had brought the rope and some gears so the plan was to make use of them. On hindsight I should have brought the 30 m rope as then I could have run out the entire pitch to an existing rappel station. The 20 m rope did the job but I had to build an intermediate anchor to belay Erica up. I made a few harder moves by going straight up but mostly for fun and for Erica to also do some rock climbing. For the second (shorter) pitch I ran out to the summit and used my own sling to build an anchor. We then chilled on the summit for at least half an hour while waiting for the Ohio group to show up, but they never did.

Erica sending the first pitch of the summit tower

Summit Panorama from Mt. Thielsen. Click to view large size.

A zoomed-in view of Mt. Scott, the highest peak at Crater Lake

Another photo of Diamond Lake with Mt. Bailey

Our group selfie on the summit, as usual.

We eventually had to descend while they were still pitching things out. Instead of down-climbing we both made a 10 m rappel off the existing anchor, and that bypassed the other party. I then belayed Erica to down-climb the lower pitch and then down-climbed myself without a belay. The descent afterwards was uneventful and we got to talk to a few other parties about the climb and the trip overall. Our round trip time was 6.5 hours and then I drove us straight south towards Crater Lake. We still had most of the day available and we wanted to make the most use of it.