Our goal had been the original route on Mamostong Kangri (7,561m). The approach is from Skyangpoche, up the Mamostong Glacier and then east, crossing a col on the south ridge to reach the upper Thangman Glacier. Camp 1 was located at 5,454m, at the junction of the Mamostong Glacier and a side branch leading to the col. However, trying to descend the far side of the 5,807m col, we found a huge crevasse that proved impossible to cross. We retreated to Camp 1, from where we had noted a nice unclimbed peak immediately to the southeast.
All of us climbed the prominent central couloir on the west face and continued along the airy crest north to the summit. We named the route Sin Permiso (750m, AD+). We equipped the route for a rappel descent.
Jonas Cruces, Spain