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Trou de la Mouche - Grand Crêt to Paccaly Traverse

La Clusaz & Le Grand Bornand

An accessible but highly rewarding Aravis classic

Ski Touring Difficult

7.1 km
1.1 km
1.1 km
4-5 hrs
Low Point
1.4 km
High Point
2.4 km
Trou de la Mouche - Grand Crêt to Paccaly Traverse Map

The Trou de la Mouche - or Flyhole - ski tour involves 1,100m of ascent up the Grand Crêt combe. The 'summit' is a spectacular hole in the Aravis limestone that you pass through before making the descent back down the combe of Paccaly.


The tour starts at the Confins car park which is located about 5km from the nearby ski resort of La Clusaz. It is an extremely popular route and can be busy during weekends and peak holiday periods.

If you're looking to avoid sharing the skin track with too many others then we advise making the trip during the week but even when it is busy, you can almost always find fresh tracks and a sense of solitude as the environment is so huge and easily absorbs ski traffic.

The ascent of Grand Crêt is reasonably straightforward but just be conscious that sluffs and slides often come down from the Paré du Joux on your left as you begin so stay in the middle of the combe if you can. Continue straight up the Grand Crêt, finding the safest and most appropriate route until you reach around 2,000m. At this point you need to strike left (north) up steeper terrain in the direction of Roche Perfia (2,499m) and towards the Trou itself (located at 2,467m to the left of Roche Perfia).

The terrain does get pretty steep about 50-100m below the Trou so you'll probably have to remove your skis and bootpack the final meters - unless you're a seriously proficient and/or determined ski mountaineer!

At the top there is a reasonably large and flat area to transition, eat snacks and take pictures without feeling cramped or stressed by other skiers/groups. The views are spectacular so make sure you take it all in.

Once you pass through the Trou, you have several descent options based on skill level/snow conditions but care is required on all routes as the initial section is reasonably steep. Head left for the steepest slopes or right for slightly less demanding terrain.

The combination of the N/NE facing aspect and relatively sheltered terrain holds snow well when other more exposed itineraries can get hammered by sun and wind.

Enjoy the spectacular big mountain environment and make your way towards the base of the combe, sniffing out the best snow and the safest route. Make your way through a small forest before joining the path that runs from the wooden Paccaly farm back in the direction of the Grand Cret.

This track will lead you back to where you started at the car park in Confins.



Serious gradient of 30-38 degrees where a real risk of slipping exists.

Medium Exposure (E2)

2 out of 4

As well as the slope itself, there are some obstacles (such as rock outcrops) which could aggravate injury.


3 out of 4

Little chance of being seen or helped in case of an accident.

Best time to visit

between February and April


  • Bowl
  • Face
  • Single Descent
  • Ski Mountaineering

Equipment required

  • Skins

Similar routes nearby

Guidebooks in this area