The most commonly misspelled peak in Oregon and one of a handful of alpine rock routes, this is a fairly easy day climb. It may look quite challenging from the start, but the technical climbing is just one pitch of easy 5th class rock at the top. Duct taping your boot tops is recommended for the scree descent. An apres climb swim in Diamond Lake is recommended.

Known as “the Lightning Rod of the Cascades”, the striking summit of Mt. Thielsen is the 7th highest peak in Oregon. The peak was named for a pioneer road builder, Hans Thielsen. It is similar in age and structure to Three Fingered Jack and Mt Washington, where glaciation and other types of erosion have left a relatively solid exposed plug of basaltic andesite. The plug is excellent rock in contrast to the rest of the mountain, which is generally poor. There is a small remnant glacier on Thielsen, and thus summiting this peak qualifies one for Mazamas membership. 

The first ascent was done in 1883.  

Activity Notes

Meet in the Thielsen Trailhead parking area at 730AM Saturday, Sept. 25. Hike up and east 3 miles to the Pacific Crest trail. Cross it and hike an ascending traverse on a well worn climber’s trail (loose rack and scree) one mile up the West Ridge to the base of the summit horn’s east face. From the base of the horn, climb the southeast side on one short pitch of fairly solid class 3-4 rock. We will have ropes for the party, although the route is often done free.  The summit is rather small, so we may have to take turns sitting on it. Elevation Gain, 4100 ft. Distance, 8 miles, round trip. Time, 6-9 hours. Return to cars by 5 PM. Spend the night camping at Diamond Lake.

Other Information
Driving Distance from Portland 250 miles
Driving Time from Portland 5 hours
General Route Info summitpost mountain forecast
Expected Duration Car to car in one day
Relevant Books Oregon High by Jeff Thomas
Relevant Maps USGS 7 minute series, Mt. Thielsen and Diamond Lake Google map
Useful Links