Montenvers railway and the Mer de Glace

The Montenvers railway is a metre-gauge rack line of 5.1km that climbs from a station beside the main one in Chamonix to Montenvers at 1,913m, on a shoulder above the Mer de Glace. It was opened in stages and inaugurated over its whole length on 29 May 1909, French Wikipedia records, and it runs on a Strub rack from end to end, at gradients of up to 22 percent. The Compagnie du Mont-Blanc worked it from 1953 until 2024, since when the Département de la Haute-Savoie, which owns the line, has run it through a régie of its own.

The Mer de Glace runs for about 7km from the foot of the Aiguille du Tacul to a snout at around 1,500m, and it is the reason the line was built. It has also been shrinking for as long as it has been measured: between 1905 and 2005 it lost 120m of thickness, and between 1830 and 2010 it lost 2.5km of length and more than 150m of thickness. That is why reaching the ice from Montenvers now means a short cable car and then a staircase, and why the staircase has had to be lengthened again and again as the surface dropped. The operator gives 170 steps to the ice cave at 1,760m, a cave recut in the glacier every year; English Wikipedia records 580 steps by the early 2020s, so the figure on any visit is the one the operator gives at the time.

At the top station there is the Glaciorium, the operator’s exhibition on glaciers and climate, a restaurant, and rooms for the night at the Montenvers refuge. Dogs travel on a lead, the operator says, and it warns that the cave stairs need care with them.

This is the rest-day page for a week based in Chamonix: no walking is needed to see the glacier. The cave is not for anyone who cannot manage the stairs, because the operator states there is no step-free access to it; for a glacier seen without a staircase, the Bossons glacier walk climbs 268m on foot to a viewpoint over the ice, and the Grand Balcon Nord arrives at Montenvers on foot for anyone who would rather earn the view.