Trois Monts Route | Mont Blanc 4,810m
At 4,810m, Mont Blanc is the highest peak in Western Europe. Unlike many highest peaks, Mont Blanc is guarded by numerous challenges and hazards, no matter which route to the top is taken. The Trois Monts (3 summits route) is slightly harder than the Goȗter (normal) route and can change dramatically based on conditions on the route. The advantages are that it provides more interesting climbing, shows a different perspective on the mountain and typically sees much less traffic than the Goȗter.
Overview | Trois Monts Route
The Trois Monts Route ascends Mont Blanc from the Refuge des Cosmiques and ascends three peaks in the process, Mont Blanc du Tacul, Mont Maudit and Mont Blanc. Most climbers choose to bypass the summits of Tacul and Maudit and only summit the highest peak of Mont Blanc as adding in summit of the other two adds significant time and challenge to the route.
After reaching the top, climbers descend either the Trois Monts or the Normal Route (Goûter Route). Climbers choosing to descend via the Goȗter Route spend the night at the Goûter Hut or to the Tramway du Mont Blanc, a train that provides service from Saint Gervais to the Nid d'Aigle Hut.
The Trois Monts route has unique challenges and hazards to taking the Goȗter Route and provides a unique opportunity to traverse the mountain. Climbers who choose to traverse are given panoramic views of the entire Mont Blanc amphitheater from east and west perspectives.
Statistics | Trois Monts Route
Vertical Gain: 4400' / 1350m (Refuge des Cosmiques to Mont Blanc Summit)
Distance: 4.2 miles / 6.8 km
Hazards:
- Serac Fall (While Ascending Mont Blanc du Tacul)
- Avalanche hazard on Tacul and Mont Maudit
- Crevasses / Bergshrunds
Technical Difficulty: Steep snow, glacier travel, moderate ice climbing (AI2)
The Start | Trois Monts Route
The Trois Monts Route starts at the Refuge des Cosmiques. Originally a site for studying cosmic rays in deep space, the Cosmiques Hut was rebuilt as a comfortable basecamp for alpinists looking to climb various routes on Mont Blanc Massif and surrounding granite spires. The refuge is a short, 30-minute approach across a glacier from the top terminal of the Aiguille do Midi.
The Refuge des Cosmiques is a wild accommodation set on the edge of the Valley Blanche Glacier at 11,700' (3600m). A 30 minute descent from the Aiguille du Midi cable car bring you to a massive lodge, equipped with a full support staff that provides dinner, breakfast, baked goods, beer, wine and bottled water to up to 130 guests at a time. The bunk rooms are large and with thick foam mattresses, comfortably sleeping roughly 20-25 people per room. For an additional 50E or so you can upgrade to a private room, which is a great option for light sleepers. Pillows and comforters are provided so that guests only need to provide a sleeping bag liner. While there is no running water for guests, there are indoor pit toilets and hand sanitizer.
Each morning, breakfast is available at all times of night from midnight through 7am. Depending on your team's climbing objective, you can choose whichever time works best. You can pick a breakfast time that works best for your team's itinerary. Whether your destination is one of the huts on the other side of Mont Blanc (the Goȗter or Tête Rousse), the Tramway du Mont Blanc or back down the Trois Monts to the Aguille du Midi, make sure you leave plenty of time to get where you need to go!
The Climb
Setting out from the Cosmiques Hut, the climb starts with a short descent and traverses to the base of the Triangle du Tacul where the route starts an upward track up the northeast face. Right out of the gates there is a steep 100' step of 40+ degree terrain, that is helpful to be on a short rope interval or pitch it. Guided parties will be short roping or short pitching this section, before the slope slacks off and becomes a consistent 30-35 degree traverse. Along the way there are a few crevasse crossings and exposure to serac fall from above. It is very helpful to take a picture of this face from the Cosmiques Hut as a reference for both the crevasses along the way and to understand where the serac hazard is greatest.
The North Face of Mont Blanc du Tacul has very few areas without exposure to serac fall. It's not a place to take a break or enjoy the views - climbers are best served to move steadily through this section. Late in the 2024 season, a serac fall killed a climber on section and it is always a hazardous section of the climb. Completing this entire stretch (about 2 hrs) in a single push before taking a break on the shoulder of Mont Blanc du Tacul ( 13,400' / 4100m) is important for getting through this section quickly. The shoulder is free of overhead hazard and is typically much less windy than the Col Maudit (13,200' (4020m)).
After the short descent from the MB du Tacul shoulder to the Col Maudit, the climb ascends to the shoulder of Mont Maudit. This is another long stretch without good break spots, some overhead hazard with ice and rock, and a pitch and a half of steep climbing 45+ degrees at the Col du Mont Maudit (14,150' (4300m)). Depending on conditions, the pitch of steep climbing from the bergschrund to the Col could be climbed with a short rope in excellent, snowy conditions or pitched out when icy. 55m above the shrund is a 2-bolt anchor with a rap ring that comes in handy on the descent or if you're pitching that slope out. From the anchor, parties typically navigate around the plug of granite with the anchors to easier ground or go directly to the ridge/Col. This is a great spot for a break, but be quick and make room for other parties coming through to not jam up the works.
From the Col du Mont Maudit, the route traverses below the summit of Maudit to the Col de la Brenva, a flat spot that would be great for breaks if it wasnt for the incessant wind. It's a great spot to break if the wind isn't blowing you over, and there aren't many sheltered areas above, so it's good to grab a quick break here regardless.
Above the Col de la Brenva is a moderate pitch that leads to a rocky outcropping at 15,000'. This is a perfect last stop before the final push to the summit if the winds aren't horrific. From here to the summit is easy glaciated terrain, but most teams slow down on this section due to the altitude.
The Descent
From the summit of Mont Blanc there are two viable options to descend the Trois Monts Route. Climbers can return the way they came via the Trois Monts Route or descend the Goûter Route. Either option requires planning ahead. If you descend via the Trois Monts, you'll need to have a reservation at the Cosmiques Hut or time your round trip with enough margin to catch the last tram back to town from the Aiguille du Midi. Descending via the Goûter will require reservations at the Goûter Hut (usually the best option so you don't have to cross the Grand Couloir in the heat of the day) or Tête Rousse Hut. It is possible to descend to the Tramway du Mont Blanc in the same day, but that would require extraordinary speed, endurance and favorable conditions in the Grand Couloir.
Descent via the Goȗter Route
This option avoids the steep and sometimes ice pitches of the Trois Monts, but adds knife edges snow and the 3rd and 4th class rock terrain of the Aiguille du Goûter. From the summit, the route drops to the northwest along a knife edge ridge of snow. Both sides are exposed so traveling close with the rope shortened is much safer and more efficient. Teams with long glacier intervals put others at risk and slow everyone down with long, drooping ropes and team members traveling over different terrain at the same time. Shortly after leaving the summit, you'll reach the Rocher de la Tournette, a rock feature just before the Bosses, two large "Bumps" on the ridge that are easy to spot from a significant distance.
Often a variation to the ridge extends out on the North Face of Mont Blanc just below the Rocher, following a flatter path on a bergschrund. This can be a great option if there are a lot of parties ascending and descending the knife edge ridges of the Bosses and is actually less steep than it appears at first glance.
Once below the Bosses, the route becomes less exposed and descends to the Refuge Valot (14,300' (4350m), a primitive shelter with an outhouse toilet. This is an emergency shelter but can be used as a break spot if the weather is nasty. From the Valot, the route descends to the Col du Dome, then ascends up to the Dome du Goȗter.
The Dome du Goȗter to the Refuge du Goȗter is a straightforward glacier descent if the visibility is good. The glacier is broad and featureless here, so a good GPS track is critical to get to the Refuge if visibility is low and the bootpack disappears. There are a couple of crevasse crossings on the planar part of the glacier and another significant one on the ridge before the hut.
Descent below the Goȗter involves crossing the Grand Couloir, a part of the mountain with significant objective hazard from rockfall. This section is particularly active and dangerous with warm temperatures and is best avoided in the heat of the day. With high freezing levels, it's best to avoid the Grand couloir in the afternoon and a stay at the Goȗter Hut is the best option to wait to cross the couloir in the coldest part of the day.
Below the Goȗter is about 2,000' of exposed 3rd class terrain to reach the Grand Couloir. For experienced scramblers, comfortable with exposure with fresh legs , this section only takes about an hour to an hour and a half. At the bottom of the ridge, the grand couloir is a 250' wide funnel. Early in the season, the couloir is filled with snow. It's less hazardous when the couloir is filled with snow as the snow can catch some of the rock, but when the snow is particularly soft, the rockfall can cause the couloir to avalanche. When the couloir is dry, the rockfall can be really fast. The most dangerous time to cross the Grand Couloir is just after the snow recedes from the couloir when there is still significant melting and freezing unseating the rock in and above the couloir.
Once through the Grand Couloir the Tete Rousse Hut is just a couple hundred feet below. The Trail du Mont Blanc leads from there to the Nid d'Aigle Hut where the Tramway du Mont Blanc picks up passengers to bring them back to Le Fayet or Les Houches via the Bellevue Cable Car. Check with a few people on the logistics around the trains - work on the lines can throw off the schedule and it can be difficult to find people who know what the actual train schedule is!
Descent via the Trois Monts Route
Descending via the Trois Monts Route seems to be a more popular choice, although it is a more involved descent than going to the Goûter Hut. From the top, retrace the steps of the ascent. The sections that provide the most challenge are the
Logistics for the Trois Monts Route
- Hut reservations at the Goȗter Hut (or Tete Rousse or Nid d'Aigle) for night 2
- Descending down to the Tramway du Mont Blanc in time to catch the last train back to town
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About the Author
Zeb Blais is an IFMGA Mountain Guide based in Truckee California. He loves all the disciplines of mountain guiding - ski, rock and alpine climbing - and tries to spend as much time as he can in the French, Swiss and Italian Alps. He has summitted and skied Mont Blanc 8 times via 3 routes and loves showing his clients the splendor of Europe's highest peak.