UN 13,631B is yet another Class 3 summit found along the ridge that extends south from Pyramid Peak in the Elk Mountains. This is typical Elk Mountain terrain with the infamous maroon rook that's loose, friable and untrustworthy. The three summits can all be completed in one day by very strong parties. For those who want to spread it out a little, we have assumed a backpack "approach" to a base camp up West Maroon Creek and climbing the summits from that location. The West Maroon Creek trailhead may be reached by most any passenger vehicle, but during summer months, restrictions apply as to hours in which one may drive up the Maroon Creek Road.
For quite a few years now, in order to regulate and reduce the vehicle traffic flow to Maroon Lake, the Forest Service has restricted vehicle traffic to Maroon Lake. Go to this link to search for detailed information: fs.usda.gov/whiteriver, but generally speaking, you can only drive a vehicle in before 9:00 AM or after 5:00 PM. Limited parking is available and can fill up rapidly on summer days. If arriving between 9:00 AM and 5:00 PM, you'll be required to ride a shuttle bus that runs every 20 minutes up to the lake.
From State HWY 82 on the west side of Aspen, drive through the traffic circle south heading for the Aspen Highlands Ski area and Maroon Lake. This traffic circle is about 1 mile west of Aspen on HWY82 or 40 miles SE from Glenwood Springs, and after the airport and Aspen Business Center by the airport. The road number is CR13. The so-called "welcome station" is 4.7 miles south and that's where you must pay a vehicle use fee of $10. If attempting to drive in during restricted hours, you'll have to park at the Highlands Ski area and ride a free shuttle in. The trail to Crater Lake is what you need to locate at the SW end of the parking lot. The trail goes around Maroon Lake on the north and west side.
Designated, fee campsites are available at the Silver Bar CG, the Silver Bell CG and the Silver Queen CG along CR13 as you drive in to Maroon Lake. These campgrounds are almost always occupied, especially on weekends. The White River National Forest website indicates that sites in these campgrounds can be reserved by calling 1-877-444-6777. There is no at-large camping allowed anywhere else along the road to Maroon Lake. Technically, vehicle camping in the parking lot at Maroon Lake is also off limits, but still practiced by many. Attempt at your own risk. The nearest other campground will be the Difficult Creek CG up HWY 82, about 4 miles east of town toward Independence Pass.
The "approach" begins at the Maroon-Crater Lake trailhead located on the east end of Maroon Lake. Watch for a registration station to obtain an overnight backpacking permit. Also plan on being required to have a bear-proof canister for food storage. The trail goes along the western shore of Maroon Lake amid the hordes of daily tourists. Many of these will make the hike to Crater Lake. This very-well-worn trail climbs steadily to Crater Lake passing the wilderness boundary (though you likely won't feel like you're in wilderness until you get beyond Crater Lake) along the way. It passes through a terminal moraine area before arriving at the lake and the trail comes to a junction near the lake on the northern end. The right fork leads up Minnehaha Creek to Buckskin Pass. For this approach however, you'll continue south on the trail that skirts the west side of Crater Lake and continues south to West Maroon Pass. There are designated campsites in the vicinity of Crater Lake.
As you continue up the trail, there is an area not too far south of the lake where the trail gains about 100 vertical feet, then loses that elevation as it crosses an area of talus. The trail also cuts through numerous areas of willows, which when laden with rain drops and drooping over the trail, will provide a nuisance of a shower as you pack through. At about the 3.75 mile point, the trail crosses from the west to the east side of the creek. A little before that crossing, you may spot some suitable campsites that we used in 1993, on the same side of the creek as the trail. More sites exists after the creek crossing, about a half mile past at the most. Basically, you want to camp somewhere near where the access is to the somewhat hidden basin below Lightening Pyramid and UN13,631B. Camping here will make it possible to reach all three summits in a day as we did or will at least make getting all three summits in two days easily possible.
There are designated backcountry campsites at Crater Lake. Beyond there, as you proceed south up the creek, there will be other primitive site opportunities, if the White River National Forest is still allowing at-large camping. Check the most current regulations before making any assumptions. Over the last couple years, White River national Forest has moved in the direction of imposing a number of new camping and backpacking regulations on this area. The following coordinates are a "best guess" as to where we found a place to camp in 1993.
Since we have included a backpack approach for these summits, the "route" begins from where the West Maroon Trail makes the first crossing from the west to the east side of the creek. When we climbed these summits in 1993, the winter of that year was a high snow year in the Colorado mountains. Those heavy snows persisted well into the summer, so our route decisions were influenced by those conditions. The three summits south of Pyramid were all climbed on the same day which was July 23, 1993. Most rate this a Class 3 climb on the assumption you stay mostly in the couloir. The difficulties we encountered staying out on the rock rib are what cause us to give this a Class 4 rating.
From the vicinity of the suggested campsite, locate where the trail crosses to the east side of the creek and make the crossing however you can. There was no log bridge of any kind at the time we did this. On this occasion, there was a snow-bridge that made crossing easy. Once across, head east up through trees, working your way along by finding whatever trails you can - some game, some man-established. There are an alternating series of cliffs and benches with areas of trees. In 1993, we found a fairly direct, cairned trail that led us through a boulder field, then alongside a steep, snow-filled gully to another bench area. From there, the route into the upper basin at about 11,800 feet opens up rather naturally. By the time of this writing, we would expect there to be a well-used/marked trail.
Once in the isolated upper basin, there are any number of possibilities for heading south, up the basin. Since this area faces north and is fairly sheltered from the sun, the snow in some areas may not melt out until later in the summer. The general rule is that the west side of the creek has more tundra while the east side is almost all talus. Since you'll have plenty of loose rock/talus to deal with later on anyhow, head up the basin on the west side of the creek making as much use as you can of areas of tundra and stable rock. The real work will begin when you reach about 12,100 ft. This is when things steepen and the tundra begins to play out. If you arrive here earlier season, be prepared for snow and bring an ice axe. The snow can be a big help in avoiding so much rubble and scree. Above 12,400 you'll want to swing more to the SE and aim for the saddle between Pt. 13,586 and UN13,631. At one point we encountered a brief ramp of small boulders and talus. They tended to be covered with lichens and moss - a deadly combination if wet. The final 400 feet of ascending to the 13,300 foot saddle will be exclusively on small boulders and scree - an unpleasant combination for secure footing of any kind.
Once at the saddle, turn south and follow the ridge to the summit. There will be some small cliffbands to navigate through or around, but generally you can stay on the the ridge and keep things at a harder 3rd Class with no real obstacles to slow your ascent. Much of this route up we found to be cairned in various spots. Enjoy the amazing view of the Bells and surrounding peaks, then begin the trip back down. The descent from the saddle will be loose. We found ourselves often sending small boulders careening down the mountainside. If there is snow, enjoy a speedy glissade back down. Pick up your trail coming up from West Maroon Creek and retreat to your campsite or make the long trudge back out to Maroon Lake. As we indicated on Thunder & Lightening Pyramid, we actually completed all three of these summits in one day, but had not planned on doing that. From the suggested backpacking campsite, we ascended into the upper basin, went up Lightening Pyramid, traversed to Thunder Pyramid, descended back into the upper basin, then ascended UN13,631B, followed by a hasty retreat back to the campsite because of weather closing in. Doing all three was a long day affair with over 5,000 vertical feet of gain.
Just for your amusement and to demonstrate that the weather in Colorado can do anything it wants, any day of the year as we tell friends, once we completed the three summits this day, we went back to our campsite and as we headed for bed that evening, a light mist was falling that continued through the night. Didn't think much of it, but the next morning when we finally arose and had enough light to see, from about the 11,000 foot level up, all the peaks were covered with about 2 inches of new snow! Remember, this was July 23. You never know what the weather is going to do.