Mixup is a great wedge of rock standing almost 4000 feet above Cascade Pass in the Washington's North Cascades. For many parties it is the first of many summits along the Ptarmigan Traverse. Others hike up the Cache Glacier, directly under the steep, 800-foot E face, unable to believe that any rock that steep and exposed can be called a Class 3 climb. The mountain's unusual structure makes whole E Face route Class 3, except for a little bit of Class 4 at each end.
Climbers familiar with the Yosemite Decimal System and with real mountains know there are two kinds of Class 4 rock:
The ideal: the climbing is not difficult enough to warrant placing protection, but it's a little harder than Class 3, so you use a rope and belay, but you don't bother with pro along the way.
Reality: the climbing is definitely Class 5, but there's no place to place any pro, so you pretend it's Class 4 and don't make any mistakes.
The standard route up Mixup Peak has a little bit of Type 2. Naturally, it's at the very top.
Drive from Marblemount up the Cascade River 22 miles to its end, then hike the trail to Cascade Pass. Turn right, and ascend Mixup Arm and traverse E and up to the Cache Glacier.
from at or near Cascade Pass. The green ridge leading up to it is
Mixup Arm. An unofficial, but distinct climbers' trail leads up the
arm, then traverses this side of it and passes over the left skyline
to reach the Cache Glacier. Photo by rfbolton.
Read the Ptarmigan Traverse – Stage 1 page for much more information. You'll follow the PT as far as the middle of the Cache Glacier, then branch toward the right-most notch in the cliffs.
There are other routes and approaches to the peak. My 1977 edition of the Cascade Alpine Guide – Stevens Pass to Rainy Pass (Fred Beckey, The Mountaineers Press) lists five other routes, all of which normally start from the N Fork of the Cascade River. You might approach the S face from the end of the Middle Fork trail, but it would take some navigating on the steep terrain. My own first introduction to the Middle Fork valley was a rescue mission to find a climber injured trying to descend that way.
You'll need a Northwest Forest Pass to park at the Cascade Pass trailhead. If you're doing the mountain as a day trip, no other permits or fees are required. If you'll be camping, you'll need a Backcountry Permit. It's free, but must be picked up the day of your trip or the day before. More info and links about both permits can be found on the Ptarmigan Traverse “mountain” page.
Camping is not allowed at or near Cascade Pass – it's fragile and over-loved. Once you've left the car, the closest camping is beyond Mixup, at Kool-Aid Lake. That would give you the opportunity to bag Magic and/or Hurry-up Mountains before heading home on a weekend trip.
There are a few sites near the parking lot, and a few miles down the Stehekin River trail, E of the pass. Read this page for more info.
of us mortals call this a summer climb. In winter you'd have to ski
or hike several miles to reach the parking lot, and the easiest
routes are on the E and N faces. The approach trail to and beyond
Cascade Pass involves some major avalance slopes. That said,
somebody's probably climbed it in winter.
The area collects a lot of snow, and the road sometimes washes out a mile short of the end. The North Cascades National Park latest conditions page has links to roads and trails. Call the visitor center in Marblemount at (360)873-4500 ext. 39 for the very latest conditions. The National Weather Service has a point forecast web page that pretends to predict the weather anywhere in the mountains. Read it, then bring clothes and gear for every imaginable condition. This should be very close to Cascade Pass.