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Mount Thielsen: West Ridge

The standard route on one of Oregon’s most recognizable peaks.

Alpine Climbing Moderate

14 km
1.1 km
1.1 km
Low Point
1.7 km
High Point
2.8 km
Mount Thielsen: West Ridge Map

Of all the Oregon volcanoes, Mount Thielsen appears as one of the most imposing in form. Its summit is a singular crooked spire jutting dramatically upward, making it the tallest thing around in this region of the Cascades. On most aspects, it looks completely unyielding, but the west ridge alone offers a clear route to the summit. This is largely a hike along the ridge, followed with a final stretch of exposed but nontechnical scrambling up the pinnacle.


The route begins from the Mount Thielsen trailhead near Diamond Lake. From there, a hiking trail leads through the forest, starting out rather flat but gradually steepening. Eventually, it becomes a climber's trail going up the ridge and breaking above the treeline. The views get really spectacular, and the hiking remains straightforward until the base of the pinnacle.

Once there, the ascent turns into Class 2 and 3 scrambling, following a gully to a notch on the south face. The final 80 feet or so is much steeper, but should never exceed Class 4 moves up blocky basalt. The fall hazard is real though, so some parties opt for rope and trad gear. There is also a fixed anchor near the summit, so a rope could be used for rappelling this section instead of downclimbing. The top is a narrow and wildly airy summit, with a thousand feet falling away on all sides. From this vantage, one can see quite far up and down the Cascade Range, and Crater Lake is even visible to the south.

Note that this route is done in all seasons, but most commonly in summer when it’s snow-free, making a beginner-friendly alpine climb. Colder conditions can add significant difficulty and technical demand to the route. The peak is also notorious for lightning strikes, so be extra cautious of weather.

Sources: https://www.summitpost.org/west-ridge/155580 https://www.fs.usda.gov/recarea/umpqua/recarea/?recid=63524



May involve slightly more complex glacier hikes, easy but possibly long rock ridges and steep snow up to 45 degrees. Equivalent to PD, PD+

High Exposure

3 out of 4

Much of the route is difficult to protect and a fall could be disastrous at certain points.


3 out of 4

Little chance of being seen or helped in case of an accident.

Best time to visit

between April and November

Guidebooks in this area