Montenvers train and Mer de Glace: timetable, prices and journey time

Twenty minutes each way. In the steam era the climb took 50 to 55 minutes; electrifying the line in 1953 and 1954 cut it to 20 minutes. The six electric railcars carry up to 160 people each, and two diesel locomotives complete the fleet. The operator allows 2 to 2.5 hours for the visit, round trip included.

Chamonix station sits at 1,042 m and Montenvers station at 1,913 m: 871 m of elevation gain over 5.1 km, with gradients reaching 220 mm per metre. The track is metre gauge (1,000 mm) and the train runs on a Strub rack, a toothed centre rail. The route crosses the Grépon tunnel (306 m), the Planards tunnel (95 m) and the Montenvers viaduct, 152 m long on eleven arches.

Work began in May 1906. The line first opened as far as kilometre 4.541 on 9 August 1908, the first works train reached the upper Montenvers station on 7 November 1908, and the complete line was inaugurated on 29 May 1909. The single-day ridership record dates from 14 August 1975 with 22,894 passengers, the annual record from 1990 with 1,008,305 passengers. Compagnie du Mont-Blanc ran the line until 2024; since November 2024 it has been managed by a public body of the Haute-Savoie department.

The train runs from 1 June to 1 November for the 2026 summer season. From 14 September to 1 November, service runs from 8.30 am to 4.30 pm, with a last ascent at 4 pm and a last descent at 4.30 pm. The operator lists the gondola as closed from 28 September to 16 October inclusive, and the ice cave as closed from 28 September until it reopens in December. A winter 2025-2026 price list also exists, with reduced winter service. These times are given as indicative by the operator and may change.

France's largest glacier: 7 km long, about 40 km² and up to 300 m thick in its accumulation zone, fed by the slopes of the Mont Blanc massif including the Géant glacier. Its snout lies at around 1,500 m. The ice flows at about 70 m per year in the middle according to the site operator; measurements from 2005 give 120 m per year in the upper section and 90 m per year near the lower limit.

The gallery is hand-cut into the glacier and remade each season, at about 1,760 m, for 350,000 visitors a year. A first cave had been dug from April to late June 1863: a 25 m gallery leading to a rotunda. Today's annual cave descends from the one Georges Claret created in 1946. It opens later in the season than the train, once the new galleries are finished.

It descends from 1,908 m to about 1,700 m, over 580 m of length and nearly 200 m of vertical drop, in 2 minutes, with a capacity of 1,500 people per hour in each direction. Built between 2021 and 2024 on six pylons, it replaces the cable car installed in 1960 and then the 1988 gondola. Its lower station stands about a hundred steps from the ice cave. Before it, the staircase had grown longer as the glacier's surface dropped, up to 400 to 580 steps depending on the published figures.

Between 1830 and 2010 the glacier lost 2.5 km of length and more than 150 metres of thickness. The study by Nussbaumer, Zumbühl and Steiner published in 2007 in the Zeitschrift für Gletscherkunde und Glazialgeologie puts the average lowering of the surface at 30 cm per year between 1939 and 2001, the equivalent of 700 million cubic metres of water. Over the 1905-2005 period, thickness fell by 120 metres. In the early 2000s the glacier was losing an average of 4 to 6 metres of thickness and some thirty metres of length a year.