Two trail options exist for TMB hikers traveling between Champex and Trient. The standard route follows the Alp Bovine trail, offering unique views high above the town of Martigny but without any major passes to cross. A second, far more challenging option crosses the high Fenêtre d’Arpette, bringing hikers close to glaciers and across rugged boulder fields. It’s widely considered the most difficult section of the Tour du Mont Blanc.
In this post, we’ll break down the Fenêtre d’Arpette route and help you prepare for this demanding yet rewarding variant.
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Fenêtre d’Arpette Variant – Stage Overview
Champex → Trient / Col de la Forclaz
Variant Route
15 km | 9 mi
1350 m | 4400 ft
1500 m | 4900 ft
7 – 9 hours
This is the variant stage we most often get questions about and for good reason – the Fenêtre d’Arpette is the most challenging section on trail on the TMB. However, for fit hikers the rewards are well worth it as you’ll experience a high alpine trail with up close views of the Trient Glacier.
The route should only be hiked in clear weather and with an early start, but for those up for the challenge this is a tremendous trail that is sure to be a highlight of your TMB.
Want to see how the Fenetre d’Arpette fits into your Tour du Mont Blanc?
In our TMB Trek Planner, you can easily add the Fenêtre d’Arpette variant to your itinerary, compare it directly with the main route, and see how it affects distance, elevation, and daily stages.
It’s a great way to decide whether this spectacular variant makes sense for your itinerary—before you ever set foot on the trail.
For hikers traveling in the traditional anti-clockwise direction, the route begins on the edge of Champex, where you’ll leave the main TMB near the La Breya chairlift. Cross beneath the lift and follow a wide track before entering the forest on a smooth trail that runs alongside a bisse. You’ll notice paths on both sides of the water channel—either works, but we recommend the left-hand trail as it’s slightly more direct. The two rejoin further along.
You’ll soon meet a narrow road and arrive at Relais d’Arpette. If you’re certain you’ll be taking the Fenêtre d’Arpette route, this can be a smart place to stay, saving you some distance the following day. It’s also the last opportunity for services before the pass, so be sure to stock up on anything you may need.
Beyond Relais d’Arpette, the route begins the long climb up the Val d’Arpette, initially on a mix of wide track and trail. About 2 km past the refuge, the track makes a sharp left turn, while the trail to the Fenêtre d’Arpette branches off to the right. From here, you’ll be on narrow singletrack—first through forest, then into increasingly open terrain as the vegetation thins with altitude.
There are a few small streams along this stretch, so take the opportunity to refill water if needed. Filtering is recommended, as livestock are often present higher in the valley.
As you climb, the views begin to open up, and you may catch your first glimpse of the narrow notch high above—this is the Fenêtre d’Arpette. The trail remains good here, but the gradient steadily increases, so pace yourself, take breaks, and enjoy the scenery.
Roughly 5.5 km from Champex, you’ll reach a junction where the Fenêtre d’Arpette route takes the right-hand fork. It’s marked by a small red blaze on a rock and is easy to miss if you’re not paying attention.
Beyond this point, the trail steepens further. The terrain becomes slightly exposed, with a drop-off to your left, though it shouldn’t pose a problem for most hikers in dry conditions. The views continue to improve—looking back, the entire valley opens toward Champex; ahead, rugged peaks rise above you, with the pass just visible depending on your angle.
With about 0.5 km remaining to the col, the trail disappears into a large boulder field. The route is marked by red and white paint blazes and occasional cairns. Snow can linger here well into July, and if present, extreme caution is required, as it may conceal unstable rocks or gaps between boulders. Take your time—this is the most technical section of the hike. After navigating around a particularly large boulder, the trail reappears, and a final steep set of switchbacks leads to the Fenêtre d’Arpette.
At the top, the narrow notch offers spectacular views in both directions, along with a few small places to sit. Take time to soak it in—behind you lies the Val d’Arpette, and ahead the Trient Valley and the Trient Glacier.
The initial descent is rocky, though less demanding than the ascent’s boulder field. A series of tight switchbacks leads downward, all with impressive views of the Trient Glacier.
As you descend, the trail gradually improves underfoot but retains an exposed feel, with steep drop-offs to your left. Lower down, it transitions into smoother singletrack, offering a welcome chance to relax and enjoy the surroundings.
Approximately 2.5 km from the top, you’ll encounter a more technical section where the trail cuts across a slope shaped by a past landslide. A fixed rope is installed here—use it and proceed with care.
Beyond this point, the descent continues through a mix of forest and open terrain, eventually running alongside the torrent flowing from the glacier above. About 4 km from the pass, you’ll reach Chalet du Glacier—a great spot to stop for a snack and a sign that easier walking lies ahead.
Just beyond the chalet, a bridge crosses the torrent, marking the start of the Les Grands variant, which climbs toward the Col de Balme via Refuge Les Grands.
The main route continues down toward the Trient Valley, following a bisse toward the Col de la Forclaz. This section is scenic and relatively gentle—a welcome contrast to the demanding terrain above.
As the trail bends toward the Col de la Forclaz, several junctions lead down into Trient for those staying in the valley. Continuing on the main path brings you to the col, where the Fenêtre d’Arpette route rejoins the standard TMB via Alp Bovine.
Want to see how the Fenetre d’Arpette fits into your Tour du Mont Blanc?
In our TMB Trek Planner, you can easily add the Fenêtre d’Arpette variant to your itinerary, compare it directly with the main route, and see how it affects distance, elevation, and daily stages.
It’s a great way to decide whether this spectacular variant makes sense for your itinerary—before you ever set foot on the trail.
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