A good hike up the PCT and then crosscountry from Marie Lake. Round Trip took about 7 hours with lunch.
I took the Diamond Rockpile trail to the PCT, and went up to the peak shoulder. I noticed cairns in a couple of places marking climber's route departures from the trail. I took the second one I came across, and ended up with a long scree slog. Peaked out and let the scenery sink in. Great views all around, even though it was a little overcast. On the way down I followed the route along the ridge and had a much easier time. I'd definitely recommend the ridge for going up. Scree gets a little frustrating at times.
Not too hot and skeeters weren't a bother.
A couple of recommendations.........
If you have the car to get over a couple miles of roughish road, suggest you start your approach hike from PCT near Summit lake. Saves you 400' of elevation gain and makes the approach hike basically flat on best trail you could ask for.
Also, rather than heading to Marie Lake (which we did on the approach as per route description), it is easier to continue on PCT (a little over a mile from junction of the trail you take to Marie Lake) and catch the bottom of the South Ridge route right off the PCT
We found this route on the descent. It had more cairns and evidence of climber's trails, saved you some westward traversing down low and time on talus higher up. More direct, faster and easier to follow IMHO.
Used Brian's route to access Marie Lake. Having done many more climbs in the Washington Cascades than in Oregon's, I had certain expectations for the term "bushwhacking". Well, to put it mildly, my expectations were WAY off! This was a very open forest with no brush until we started to climb in earnest. Even then the brush was anything but dense, making travel very easy. A thoroughly enjoyable climb, with crystal clear air and long views, although it was a bit warm, and the mosquitos were indeed pesky.
From the north, the PCT route from Pengra Pass still has six to ten feet of snow past the Mt. Yoran junction so this is a slow bushwhack past that point at present. (July 13th 2004). I climbed Diamond Peak July 17th, 2001 by this intended route and there was no snow on the PCT so this was a big surprise this year. I intended to run/hike to the south ridge but after several miles of soft deep snow opted for a direct assault on the minor ridge up the east face. This small ridge lies between the east ridge and the south ridge and is a bit iffy near the top due to loose rocks the size of pianos but do-able with caution. The soft snow made this seem safer than such an angle of climb would usually present but I wouldn't recommend this route without crampons under most conditions. I attained the minor summit at the top of the ridge and made my way south to the true summit and was rewarded with spectacular views in all directions. This was an exceptionally good day with light winds and temperatures in the 60's. Mosquitoes were at their worst in the forest but were gone above the tree line.
A great climb in winter --- perfect to chase away winter blues. Mostly just a good workout --- fine for novice alpinists. I often carry up skis and ski the front bowl to get down. Glissading works too....
Excellent weather and no mosquitos make this the perfect season for Diamond Peak. Awesome views in every direction. Every major Cascade volcano in Oregon was visible -- from Mt. Hood to Mt. McLoughlin (except North Sister, which is hidden behind Middle). Even the Willamette Valley and the Coast Range hovering above its constant haze were visible. I saw no one else the whole day.
Left the trails behind at Marie Lake and bushwacked the final 2 miles and 2,600 ft. to the summit. Once you reach the small pond north of Marie Lake it is a fun tough scramble straight up, lots of huge bolders to hop along. The view once you reach the false summit is incredible. It was really hazy to the north, so not much to be seen, but to the south Cowhorn, Sawtooth, Howlock, Thielsen, Bailey, and Crater Lake rim clearly visible. The views of massive Diamond Peak from the summit were the highlight anyway. Had the summit all to myself for over an hour where I enjoyed the views, warm sunshine, and the traditional trail lunch of cold pizza from the night before ;-) Great day, fun bushwack and scramble, and beautiful mountain!
By the way, bring the jungle juice! Mosquitos are very bad in this area, at least in the early part of summer.
Great conditions! Rime ice covered everything, including the snowfields, creating a good hard surface for crampons. A few moats and cornices to worry about, otherwise pretty straightforward. Summit was no bigger than a large dinner table due to the pyramid of snow. Clear blue sky as far as I could see! The Three Sisters, Jefferson, and Hood were all visible as well.
Two days on the peak. Woke to 18" fresh the morning we had to leave. Aaaaargh!
For the first 3 miles, there's a trail through the woods and I think someone who looked like me must have really pissed off the skeeters because they were swarming me the whole first third of the climb. Once I reached Marie Lake it got fun as that's where the trail ended and I had to bushwhack north about a mile or so until I could start picking out the ridges on the south side. Traversed a few ridges to the left until I picked up the main South Ridge. From there I spotted a few cairns and someone even used an ancient ski pole to point the way. That's as much of a trail as you get on this one. Made the false summit and saw the cool knife edge ridge over to the main summit. Nice scramble over some gendarmes and I was there. Beautiful day but kinda hazy from forest fires so views limited to the Three Sisters to Thielsen. Had the whole mountain to myself the entire day. Up in 3 hrs 45 mins and down in 2 hrs 35 mins.