The Mer de Glace, the largest glacier in France, is seen from the Montenvers site (1,913 m / 6,276 ft), 20 minutes from Chamonix by the little red cog railway; a gondola and then steps lead to the ice cave, carved into the glacier every year. The glacier is retreating fast: according to a study published in 2020 in the journal The Cryosphere, its front retreated by about 35 m (115 ft) a year between 1995 and 2015. This page gives the official opening calendar, the prices published by the tourist office, accessibility, the scientific figures on the retreat and the climate in Chamonix.
The Mer de Glace is one of the valley’s headline excursions: see our ideas for visiting Chamonix and our Aiguille du Midi page, the other major high-mountain site.
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Mer de Glace: key facts
- Getting there: Montenvers train from Chamonix, 20 minutes; arrival at 1,913 m (6,276 ft) — checked on 23 October 2026 on montenversmerdeglace.montblancnaturalresort.com
- Autumn 2026: ice cave and gondola closed from 28 September to 16 October; ice cave closed from 17 October to 1 November; train closed from 2 November to 4 December.
- Winter 2026–2027: train every day from 10 am to 4:30 pm from 5 December 2026 to 12 March 2027; ice cave open from 19 December; from 13 March to 30 April 2027, 10 am–5 pm, last trip to the cave at 3 pm — checked on 23 October 2026 on chamonix.com
- Prices (tourist office): pass covering train + gondola + exhibitions + cave €49.70 adult, €42.20 child aged 5–14 or senior over 65, free under 5; train only, round trip, €31.50 adult.
- Time needed: 2 to 3 hours on average (travel and cave included), up to twice that in busy periods according to the tourist office.
- Ice cave: not wheelchair accessible (170 steps according to the operator).
The Montenvers train
The little red cog railway leaves from the Montenvers station in Chamonix and reaches the site of the same name in 20 minutes, with views of the valley and the Aiguilles Rouges. On arrival, the esplanade looks out over the Mer de Glace and two famous mountaineering peaks: the Drus and the Grandes Jorasses. According to the tourist office, a train leaves every hour or every 30 minutes depending on demand. The nearest stops to the departure station are the Chamonix Centre SNCF station and the Place Mont-Blanc bus stop; nearby car parks are the Biolay (outdoor) and the Mont-Blanc car park (underground).
What to see at Montenvers
- The panorama over the glacier: from the esplanade, wheelchair accessible.
- The Mer de Glace gondola: it takes you closer to the glacier and serves the access to the cave; it is suitable for visitors with reduced mobility.
- The ice cave: a gallery carved into the glacier itself every year. To reach it, you have to go down steps: 170 according to the operator’s website (the tourist office page says 100 steps).
- The Glaciorium: an interactive space on glaciology, the formation, history and evolution of the Mer de Glace.
- The Montenvers hut: one of the first alpine huts, with historic screenings, a restaurant and rooms.
- Hikes: the Grand Balcon Nord toward the Plan de l’Aiguille, or the walk down to Chamonix via Les Planards or the village of Les Bois.
The retreat of the Mer de Glace: what scientists say
The operator presents the site as a « witness » of climate change. The most precise figures we have read come from a modeling study published in 2020 in The Cryosphere (Peyaud, Bouchayer, Gagliardini, Vincent, Gillet-Chaulet, Six and Laarman), led in particular by glaciologists from Grenoble.
| Indicator | Published value | Period |
|---|---|---|
| Glacier length | about 20 km (12 mi) (largest glacier in France) | State described in the study |
| Observed retreat of the front | about 35 m (115 ft) a year | 1995–2015 |
| Observed thinning (Échelets section) | 5.0 m (16 ft) a year | 2005–2015 |
| Projected retreat of the front | 60 to 85 m (197 to 279 ft) a year | 2020–2030 |
| Projected retreat of the front | 65 to 95 m (213 to 312 ft) a year | 2030–2040 |
| Total projected retreat | 2 to 6 km (1 to 4 mi) depending on the 26 climate scenarios | 2015–2050 |
Destination de Voyage calculation based on this study: at 35 m a year, the front retreated by about 700 m (2,297 ft) in 20 years (1995–2015). At the rate projected for 2020–2030, it would retreat by 600 to 850 m (1,969 to 2,789 ft) in ten years, a comparable distance in half the time. The study also considered that the Montenvers section could be free of ice around 2023.
Climate in Chamonix and best time to go
Montenvers is at 1,913 m (6,276 ft), about 870 m (2,854 ft) above the Météo-France station in Chamonix (1,042 m / 3,419 ft): it is cooler there. This table gives the Chamonix normals, the most recent published on the station’s official sheet (1981–2010 period).
| Month | Max | Min | Precipitation | Days with precipitation (≥ 1 mm) |
|---|---|---|---|---|
| January | 2.7 °C (37 °F) | -7.1 °C (19 °F) | 93.9 mm (3.7 in) | 9.7 |
| February | 5.0 °C (41 °F) | -6.3 °C (21 °F) | 83.8 mm (3.3 in) | 8.4 |
| March | 8.9 °C (48 °F) | -3.0 °C (27 °F) | 86.6 mm (3.4 in) | 9.8 |
| April | 12.7 °C (55 °F) | 0.4 °C (33 °F) | 89.0 mm (3.5 in) | 10.1 |
| May | 17.6 °C (64 °F) | 4.8 °C (41 °F) | 121.4 mm (4.8 in) | 13.6 |
| June | 21.2 °C (70 °F) | 7.5 °C (46 °F) | 130.4 mm (5.1 in) | 12.6 |
| July | 23.9 °C (75 °F) | 9.1 °C (48 °F) | 119.0 mm (4.7 in) | 11.8 |
| August | 23.1 °C (74 °F) | 8.7 °C (48 °F) | 125.9 mm (5.0 in) | 12.1 |
| September | 19.1 °C (66 °F) | 6.0 °C (43 °F) | 103.6 mm (4.1 in) | 9.9 |
| October | 14.7 °C (58 °F) | 2.5 °C (37 °F) | 116.8 mm (4.6 in) | 10.1 |
| November | 7.4 °C (45 °F) | -2.1 °C (28 °F) | 100.7 mm (4.0 in) | 9.6 |
| December | 2.6 °C (37 °F) | -5.7 °C (22 °F) | 109.8 mm (4.3 in) | 10.6 |
How to read it: Chamonix gets rain all year (1,281 mm / 50.4 in a year), with a peak from May to August (12 to 14 days of precipitation a month). Summer remains the mildest season (23 to 24 °C / 73 to 75 °F maximum in July and August in the valley) and the one when the whole site is open. In winter, the cave reopens from mid-December, but minimums are below freezing from November to March. In autumn 2026, check the closures carefully: the train is stopped from 2 November to 4 December.
Accessibility
The tourist office details the arrangements for visitors with reduced mobility: 2 reserved parking spaces below the Montenvers station; sloping access to the station, with assistance; let the ticket desk know so the access bars to the train can be installed; adapted toilets on arrival; a large accessible esplanade. The path to the hut and the Glaciorium is stony. The gondola is adapted, but the cave remains inaccessible because of the steps. Dogs on a leash are accepted, with care on the steps.
Common mistakes to avoid
- Coming in November: in 2026, the Montenvers train is closed from 2 November to 4 December.
- Setting off late in spring: from 13 March to 30 April 2027, the last trip to visit the cave is at 3 pm.
- Underestimating the steps: 170 to go down according to the operator, and back up on the way out; plan for closed shoes.
- Going up in city clothes: the site is at 1,913 m (6,276 ft), noticeably cooler than the valley.
- Forgetting the weather: hours are given « subject to favorable weather conditions ».
What to see nearby
In the same valley, the Aiguille du Midi rises to 3,842 m (12,605 ft) by cable car. To plan your stay, see our Chamonix guide.
Frequently asked questions
How do you get to the Mer de Glace?
By the Montenvers cog railway, from Chamonix: 20 minutes to the Montenvers site (1,913 m / 6,276 ft), then a gondola and steps to the ice cave.
How much does it cost to visit the Mer de Glace?
The tourist office publishes €49.70 per adult for the full pass (train, gondola, exhibitions, cave), €42.20 for ages 5 to 14 and over 65, free under 5. The train alone, round trip, costs €31.50 per adult.
Is the ice cave open all year?
No. In 2026 it was closed from 28 September to 1 November; the tourist office announces its reopening from 19 December 2026.
How many steps are there to the ice cave?
170 steps according to the operator’s website; the tourist office says 100 steps. The number increases as the glacier melts.
How fast is the Mer de Glace retreating?
According to a study published in The Cryosphere in 2020, the front retreated by about 35 m (115 ft) a year between 1995 and 2015, and could retreat by 2 to 6 km (1 to 4 mi) between 2015 and 2050 depending on the scenario.
How long does a visit to Montenvers take?
2 to 3 hours on average, travel and cave included, according to the tourist office; longer in busy periods.
Our sources
- Compagnie du Mont-Blanc – Montenvers Mer de Glace (montenversmerdeglace.montblancnaturalresort.com): home page and autumn information, consulted on 23 October 2026
- Chamonix-Mont-Blanc Valley tourist office: « Mer de Glace and the Montenvers train » page (prices, hours, accessibility), consulted on 23 October 2026
- Peyaud V. et al., Numerical modeling of the dynamics of the Mer de Glace glacier, The Cryosphere, 14, 3979–3994, 2020
- Météo-France: climate sheet for Chamonix (74056001), 1981–2010 statistics
- Our methodology
Updated October 2026. Prices and hours may change: check the official website before you go.