Day 12: Argentière to Chamonix

Heatwave warning across France and much of Europe today.

It was already warm at 5am when we got up, and the forest didn’t offer much relief by 6:15.

We started from the campsite at Argentière, slightly off the main TMB line, which meant two quiet hours on trail and roughly 500m of steady ascent before rejoining the official route. Quiet, shaded, and still sweaty enough to wonder what the rest of the day had planned.

A pause for sun cream and hats revealed a small green spider doing its best impression of being important.

After that the trail tilted more decisively upwards towards the Aiguillette d’Argentière area, where the terrain starts to feel a bit less like hiking and a bit more like scrambling.

From there we moved onto the Grand Balcon Nord section, where the metal ladders begin. Exposed, straightforward, and noticeably more enjoyable before the sun fully commits to the rock.

We covered the first 5km in just over three hours. Slow going, but entirely consistent with steep ground, heat, and the general policy of not rushing anything that involves falling.

From the balcony section the views towards Mont Blanc opened up clearly as the trail followed the contour of the slope. The summit stood sharp and well defined, with glaciers and ridges spreading out across the massif. It’s the sort of section where the walking naturally slows a bit, not because it’s difficult, but because you keep finding yourself looking up rather than ahead.

The climb continued up towards Lac Blanc and the Refuge du Lac Blanc, by which point the heat was properly in charge. Even the €6 cokes at the refuge seemed acceptable.

By then we’d joined the flow of day hikers coming up from the Flégère gondola. A different pace entirely. We were heading the same way down, taking the lift back to Les Praz, which felt like a sensible negotiation with gravity after the morning’s work.

And that’s it, our TMB is complete (no time to walk back to Les Houches).

From early starts in cool valleys to long climbs in full sun, from quiet forest paths to the busier balcony sections, it’s been a steady mix of effort, views, and managing heat. Some days moved quickly, others dragged in the best possible way, but the rhythm stayed the same: walk, climb, descend, repeat.

We finished with the usual practicalities rather than ceremony - a train to Les Houches for a kit pickup, the bus back into Chamonix, and an afternoon of washing clothes and us in equal measure. Not dramatic, just necessary.

Rest day tomorrow. This blog continues for a couple of days while I travel to Spain for my next adventure on the GR11 trail.