ApproachA 06:00~07:00 start from the Mountet hut is more than sufficient no mater which route you take to the base of the climb. There are three options all starting at the hut.
1) Follow the normal route to the Zinal-Rothorn up the moraine path to the col at 3188m then left over through a boulder field up and over the col down to the NE over the small Besso glacier (sometimes icy) cross the glaiceir to the skee/neve pile at the base of the SW ridge.
2) From the hut follow the NW path that goes under the foot of the Mammouth and once around its SW foot cut NE down to the Besso glacier and across to the skee/neve pile at the base of the SW ridge.
3) From the hut follow the normal path back down the valley to a point parallel this the large skree/neve pile at the base of the SW ridge then take the line of least resistance up to the base of the skree/neve pile avoiding the Besso glacier.
At this point climb the skree/neve pile till your reach a wide chimney-couloir on the left that is a few dozen meters from the end of the pile. The pile ends in another couloir that is not part of the route.
The proper couloir is usually marked with a small cairn, this is the start of the route.
Keep away from the ridge until one is ready to enter the couloir as stone-fall from any party above can make this a rather perilous position.
Route DescriptionFollow the chimney-couloir up over loose but easy ground, be wary or stone-fall from parties above when in the couloir, over the odd short step all the way to the top of the SW ridge, (normally marked with a cairn). Remember this spot for the decent as it is quite easy to mistake one of the ridge’s other couloirs for this one.
Simply follow the ridge up through a number of III and IV steps,(rock is great) and gendarmes the hardest of which can be turned to the right until you reach the final step. This final step can be climbed directly at IV+~V or simply turn it to the right by descending a bit to easy ground and moving directly across for about 50m to a usually neve filled couloir (chiminey in some guidebooks) that leads up to the SE ridge after a pitch. Follow the SE ridge up the summit after 2 or so pitches of easy class III.
Decent is the reverse of assent and make sure you find the same exit couloir on the way down.