Ever since two English explorers, William Windham and Richard Pocock, first discovered the Mer de Glace (“Sea of Ice”) in 1741, it has become one of the world’s most visited natural sites and is a huge draw of visitors to the Chamonix Valley. The area became accessible by mule from 1802, but it was the opening of the Montenvers Train in 1908 that really opened the site up to the masses.
As well as enjoying the unique experience of the Montenvers train itself, the main draw for visitors to this site is the Mer de Glace. At 7km long and with a surface area of 40km2, it is also France’s largest glacier, extending from an altitude of 3900m, at the point where the Leschaux, Le Tacul and the Talèfre glaciers converge, down to 1400m, just below the Hotel Montenvers. The width of the glacier varies between 700m to 1950m and the depth of the ice averages around 200m but is as much as 400m thick in places!
Up until 1820, it was still possible to see the Mer de Glace from Chamonix, but since then it has steadily retreated out of sight as the vast rocky moraines along its edge will testify. However, like all glaciers, the Mer de Glace is constantly being renewed by snowfall and is permanently “flowing” under the effect of its own weight. Although this movement isn’t perceptible to the naked eye, it advances around 120m per year on the upper, steeper part and 90m per year lower down by the Montenvers viewpoint.
The most obvious evidence of this movement can be seen at the entrance to the ice grotto – an impressive cave that is carved out of the ice, enabling you to pass right into the heart of the glacier. For more than 50 years the grotto has been meticulously sculpted each year, shaping the ice into scenes depicting mountain life from the early 19th century. Inside, the light reflects off the beautiful blue ice to create a wonderfully eerie, sub-glacial atmosphere.
You can access the caves from the Montenvers train station by a small gondola lift (or via a footpath for the more energetic) and then a flight of approximately 300 steps. Entrance to the cave costs a few euros for holders of a Mont Blanc Multipass or Mont Blanc Unlimited ski pass or it is also possible to buy a combined ticket for the return train and gondola trip, plus entrance to the caves - find prices here. Wear sturdy footwear and take warm clothes with you (even in summer) as inside the caves the temperature remains at a cool 8 degrees.
During winter, one of the highlights for many visitors to the Mer de Glace is to watch skiers returning from the Vallee Blanche which ends just above the entrance to the ice caves. Thousands of people each year ski this legendary high mountain itinerary usually in the company of a mountain guide due to the glaciated nature of the terrain. It is also a great spot to watch mountaineers coming and going from their high mountain adventures on some of the classic peaks in the area – Les Drus (3754m), Les Grandes Jorasses (4208m) and the Aiguille du Grepon (3482m). In the summer, you will often see groups of people out on the ice practicing crevasse rescue techniques, ice climbing, glacier walking and a whole host of other skills that come in useful in Chamonix all year round. If you fancy learning any of these activities yourself, then contact some of the mountain guides and guiding schools via the above link.
The train to the Mer de Glace runs regularly throughout the year and the time table can be found here.
Location: Chamonix Main Town
Sight Type: Attraction - Unguided
Activities: Tours / Excursions