- Oregon County HP: #30 & #31
- Difficulty: ⭐️⭐️⭐️⭐️
- Summit Elevation: 9,182 feet
- Mountain Range: Cascade Mountains
- Ancestral Lands: Molalla; Klamath
PLANNING DETAILS
Location: Mt. Theilsen is located near the north of Crater Lake National Park, roughly halfway between Klamath Falls and Bend, Oregon. The summit bisects Douglas and Klamath Counties and serves as the highest natural point for both counties.
When to Visit: July to mid-September. Mt. Theilsen’s dramatic horn-shaped peak is nicknamed the “lightning rod of the Cascades” because of the number of times it has been struck by lightning during thunderstorms.
Fees/Permits Required: The Mt. Theilsen Wilderness permit is required for day-use and overnight stays between June 15 and October 15. This free permit is self-issued at the Mt. Theilsen Trailhead.
Getting There: Mt. Theilsen is most easily accessed from the Mt. Theilsen Trailhead on the west side of the peak. The trailhead sits directly east of Diamond Lake on Oregon Highway 138 (OR-138). The closest town with amenities is 30 miles away in Chemult, OR.
Directions from Roseburg:
- From I-5 (exit 124), head east on W. Harvard Avenue for 0.5 miles, crossing over the South Umpqua River toward downtown.
- Turn left on Stephens Ave, and drive north for 0.3 miles toward the OR-138 East (Diamond Lake / Crater Lake) exit.
- Turn right onto OR-138 and follow the highway east toward Diamond Lake for 81.3 miles.
- Turn left to exit the highway at the Mt. Theislen Trailhead, which is located between mile markers 81 and 82. (Note: A road sign alerting you to the trailhead will appear approximately 1/4 mile before the turn)
Directions from Bend:
- From Bend, follow US-97 south 74 miles, then turn right onto US-138 West toward Diamond Lake / Roseburg.
- Follow OR-138 west toward Diamond Lake for 18.8 miles
- Turn right to exit the highway at the Mt. Theilsen Trailhead, which is located between mile markers 82 and 81. (Note: A road sign alerting you to the trailhead will appear approximately 1/4 mile before the right turn)
Parking: The Mt. Theilsen Trailhead has a paved lot with room for approximately 10-15 vehicles. Trailhead parking costs $5. Visitors should note that the USFS transitioned to electronic payment only for the Umpqua National Forest. Payments are made on the Recreation.gov app by scanning the QR code at the trailhead. Parking fees are waived for those displaying a Northwest Forest Pass or America the Beautiful Interagency Pass on their vehicle’s dashboard.
Pets Allowed: Yes; however, the loose alpine terrain and Class 4 scramble up the summit pinnacle do not make this a pet-friendly hike.
Kid-friendly: Due to the length/steepness of this hike, lack of water, route-finding, and exposure on the summit, this hike is best for older teens and adults.
Hiking Distance: 9.4 miles round trip via the Mt. Theilsen Trail #1456 & climbers route
Difficulty: ⭐️⭐️⭐️⭐️ (Hard) — The established trail takes hikers up 2,000 vertical feet through a burn scar with no shade or water. Thereafter, the “climbers trail” ascends 1,600 vertical feet and requires route-finding over loose dirt, rocks, and talus. The final 80-100 vertical feet to the summit pinnacle involves an exposed Class 4 rock scramble, and a climbing harness, rope, and helmet are advisable. Weather on this mountain can change quickly, and the threat of lightning is unusually high.
The Summit: Mt. Theilsen’s summit has a brass survey marker near the top. Astute climbers may also notice numerous rock fulgurites (jagged stripes of melted, glassy rock) caused by lightning strikes on the summit pinnacle.
TRIP SUMMARY
Date Visited: August 19, 2026
Hiking Route Used: Mt. Theilsen Trail #1456 & West Ridge Climbers Trail – 9.4 miles round-trip
This wasn’t my first visit to Mt. Theilsen. The last time I was there was in 2023, when I was section-hiking the PCT northbound from Crater Lake NP. During that prior trip, I ended up camping on the mountain’s western shoulder near the junction of the PCT and Mt. Theilsen Trail, about a mile below the iconic horn-shaped spire. I was just beginning my Oregon CoHPs quest that year, and I wasn’t quite ready to climb this difficult peak yet.
A mere 3 years later, I was staring down at the remaining half-dozen peaks. I couldn’t put off hiking Mt. Theilsen any longer. I now had the skills to climb this mountain, but I didn’t want to solo.
My original plan was to do a Mt. Theilsen climb with the Mazamas climbing group. But there were an equal number of other climbers who had similar hopes. The group’s August 2026 trip had 27 applicants for 11 climbing spots, and I was waitlisted for the climb.
The Mazamas had another Theilsen climb scheduled for mid-September 2026, but I didn’t want to wait for 7 more weeks to find out that I’d been waitlisted yet again. So I bit the bullet and texted Adam, the climbing guide I’d met while taking TMG’s Alpine Climbing course earlier this summer. He and I climbed Mt. Washington together, which was much more difficult than Theilsen, and I was hoping he had an open date in August so we could do a one-on-one climb.
As luck would have it, Adam and I both had the week free immediately before I left for Iceland for my hike on the Laugavegur & Fimmvörðuháls Trails. So we made plans to meet at Mt. Theilsen Trailhead on August 19th.
Mt. Theisen’s trailhead isn’t particularly difficult to get to, but it’s a 2.5- to 3-hour drive from my home in Eugene. With a 7 am start planned, I could get up hours before sunrise and make the long drive through the mountains. Or I could turn this into a microadventure and drive out the evening before to find a last-minute campsite at one of three USFS campgrounds on the shores of Diamond Lake. The latter option won, hands down!
When I arrived at the trailhead at 6:50 am, Adam was already waiting for me. The small parking lot was empty, but for two other cars. So it looked like this midweek climb would be a quiet one.
We began by heading into the Umpqua National Forest. The Mt. Theilsen Trail (#1456), with a moderate climb of 2,000 vertical feet as we made our way up to the Pacific Crest Trail (PCT). I’d been expecting tons of mosquitoes on this climb, but there were surprisingly none! The super-low snow year or the crazy wildfires over the past month must have kept them at bay
The vibrant green Douglas Fir forest soon gave way to soot, char, and bare trees as we made our way up into a large burn scar on the mountain’s western approach. The morning temperatures were still cool on our ascent, but I knew from experience that this terrain would be brutally hot on our shadeless descent this afternoon.
Adam set a nice, easy pace for the morning’s initial 3.6 miles up to the PCT. We needed to conserve our energy for the final mile of the ascent rather than wasting it on getting up to the “real” climb.
About an hour into our ascent, we were overtaken by a fast-moving hiker wearing a running vest with a helmet strapped to the outside. Based on how quickly he was ascending, we assumed this wasn’t his first time up Mt. Theilsen. And we wouldn’t see him again until we were approaching the base of the summit horn.
When we arrived at the junction with the PCT at 7,300 feet, we met a cluster of NOBO thru-hikers. All of them had foreign accents, and I soon learned they were from France and Australia. That’s an amazingly long way to travel, and it’s a tremendous reminder of how lucky we are to have multiple 2000-mile long trails to hike here in the US.
After a quick break at the PCT junction, Adam and I bid goodbye to the thru-hikers (most of whom were excitedly checking their phones because they finally had cell service).
The next mile of our ascent followed the climber’s trail into the mountain’s rocky alpine zone. The trail was far less defined than it had been below the PCT. But it was briefly green again, with small shrubs and whitebark pines dotting the slope above us
Above us, Mt. Theilsen’s slopes had a swirling, Dr. Seuss-like formation in light tans and browns. The horn above us looked less pointy as we followed the climber’s trail east, but we couldn’t spend all our time looking up at our destination. Our more immediate challenge was route navigation.
The climber’s trail had pretty much petered out.,It was replaced by a series of braided paths resembling game trails through the loose rocks and scree. This slowed our pace considerably as we tried to figure out the best way to navigate through the loose alpine terrain.
As we hiked up toward the south side of the summit block, Mt. Theilsen’s slope turned rockier and even steeper. Finding the true path remained a challenge, and it was evident that previous climbers had ascended the next 1,000 vertical feet via various routes to find the most stable one.
As we continued up the slope, we spotted the guy in the running vest who’d passed us earlier this morning. He was now just above the base of the summit horn and was starting to ascend the mountain’s left side.
If this climber hadn’t been ahead of us, perhaps we would have double-checked our maps and the route. But we fell prey to herd mentality and followed the same route up that he did.
This move turned out to be a mistake. Neither Adam nor I had climbed this Mt. Theilsen before. We knew our route was called the West Ridge, and the climber ahead of us appeared to be climbing the west side of the horn. Yet when we arrived beneath him, his route looked far more technical than what either of us had been expecting.
The slabs of rock on this side of the horn seemed to emerge from the ground at a near-vertical slope. We stared up after the other climber, only to lose sight of him. But before long, we spotted him again as he began descending the rock toward us.
When the three of us eventually crossed paths, we asked if he’d reached the summit. He said no. He got up to the spot that he thought was called Chicken Ridge, but decided the rock above him was too loose and too steep to ascend without a rope. He was turning back and warned us to test every hold on our ascent. The rock was very loose.
We thanked him, and then began our ascent on a similar path. Adam was in the lead and set several anchors as we climbed toward the summit. This part of the climb felt much more difficult than all the trip reports I’d read before coming out here. Some of the climbers wrote about not taking a rope or helmet at all. Had they really been that bold?
As Adam climbed above me, pebbles and rocks came loose and started to rain down. I quickly tucked in toward the rock to avoid the debris, and that’s when I heard a boulder hit the slope below me and begin rolling down the mountain. This missile was the side of a medicine ball and had flown directly over me! Holy crap. This was definitely not a good route.
Adam and I called out to each other to make sure we were both okay, and then we mutually agreed this couldn’t be the right route. I pulled out my phone to check the map, and it turned out we were now on Mt. Theilsen’s Northwest Arête (a 5.7 climb), not the main class 4 route! That other climber was nowhere near Chicken Ledge! It was located on the opposite side of the summit horn. What a waste of effort.
Adam and I carefully dropped back down the rock to start all over again. As we rounded the corner at the base of the summit, we spotted two guys with small day packs resting against the rock wall. We strongly discouraged them from taking our route and then pointed them in the direction we were now headed.
That was the exact moment when I noticed that someone had drawn a chalk arrow on one of the nearby boulders. We probably would have seen this marking if we hadn’t been blindly following that other climber. Doh!
Our second route up the horn’s opposite side was significantly easier than our original (incorrect) route! After a few minutes of scrambling, we crested some boulders and were greeted with sublime views. This wide, flat area was Chicken Ledge, and it was large enough for 15+ climbers to hang out.
The final climb from the ledge took us up 80 vertical feet to the pinnacle of the summit horn. As the trip reports indicated, it was true Class 4. The rock was solid, and there were plenty of good handholds to use on the steep scramble up. But a fall would have been bad. I’m glad Adam and I came with our harnesses and a rope. That feeling of safety on exposed terrain is always a confidence booster.
The views from the top of Mt. Theilsen were out of this world. Diamond Lake sat to our west. Crater Lake National Park sat to our south, and we could see as far south as Mt. McLoughlin (the highest point in Jackson Co. and the last big volcanic peak in Oregon).
A brass survey monument was drilled into one of the highest boulders. Nearby, I spotted jagged lines of fulgurite where lightning had struck the rock, creating a black, glassy crust (aka fossilized lightning). Talk about a unique high point!
With Mt. Theilsen now under my belt, I could tick two more Oregon County high points (CoHPs) off my list. This climb was a “two-fer,” just like South Sister and Mt. Hood. I’d just reached the highest point in both Klamath County and Douglas County in a single climb. I have only 4 more to go before I finish all 36 Oregon CoHPs!
BONUS MATERIAL
Public Camping Nearby:
- Diamond Lake Campground is a USFS campground located on the eastern shore of Diamond Lake and is a short 4-mile drive from the Mt. Theilsen TH. Open seasonally from mid-June to Labor Day weekend, it offers 238 campsites, flush toilets and showers, potable water, a boat ramp, and lake access. Reservations can be made online or by using the Recreation.gov app. Cost: $24/night + fees/taxes.
- Broken Arriow Campground is a USFS campground located on the south shore of Diamond Lake, approximately 2.5 miles from the Mt. Theilsen TH. Open seasonally from mid-June to Labor Day weekend, it and offers 120 campsites, flush toilets and showers, potable water, lake access, picnic tables, and trash. Reservations can be made online or by using the Recreation.gov app. Cost: $23/night + fees/taxes.
- Theilsen View Campground is a USFS campground located on the west shore of Diamond Lake, approximately 6.5 miles from the Mt. Theilsen TH. Open seasonally from mid-June to Labor Day weekend, it offers 60 campsites, vault toilets, potable water spigots, and trash. Reservations can be made online or by using the Recreation.gov app. Cost: $23/night + fees/taxes.
Alternate Routes:
- Pacific Crest Trail (PCT) – Hikers can approach Mt. Theilsen from the south via the PCT. Parking is available at the North Crater Lake Trailhead/Sno-Park on OR Highway 138. The route follows the North Crater Lake Trail east for 0.3 miles until it intersects with the PCT. Turn north onto the PCT and follow it for 6 miles to the junction with the Mt. Theisen Trail at 7,335 feet elevation. The final 1 mile to the summit follows the Mt. Theilsen climber’s trail. The total distance for this alternate route is 13.5 miles (round-trip).
Resources:
- Highpointing Mt. Theilsen (Peakbagger trip reports)
- Mt. Theilsen Routes (Summit Post)
- Mt. Theilsen Trail #1456 & Permit Info (USFS)
- Weather Forecast (Mountain-Forecast.com)
- Mt. Theisen History (Oregon Encyclopedia)
A quick note on my difficulty ratings:
- ⭐️ = Easy hike (0-5 miles long, defined trail, flat or limited vertical gain, good for all ages)
- ⭐️⭐️ = Moderate hike (<5 miles round-trip, on trail, some vertical gain)
- ⭐️⭐️⭐️ = Challenging (5-15 miles round-trip, possible off-trail navigation, steep climbs, or bouldering)
- ⭐️⭐️⭐️⭐️ = Hard (10+ miles round-trip, with off-trail navigation, very steep climbs, and/or extra equipment recommended)
- ⭐️⭐️⭐️⭐️⭐️ = Very Hard (15+ miles round-trip, and/or technical skills or equipment required)