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.
The iconic red Montenvers train runs on a rack and pinion (or cog) railway just over 5 kilometres in length (3.2 miles) and snakes its way up from Chamonix to the top station at 1,913 metres. The train was first put into use in 1908 when the line stopped at Caillet, and then fully opened all the way to the top in 1909. Prior to the existence of the trains, the only access to the Mer de Glace had been by mule or on foot.
The train runs on a single track, with one passing point part way up to allow the descending train to pass by. Fans of mountain cog railways will enjoy the train ride by itself and on special occasions, the red trains are replaced with historic train carriages which you can book as a 'Prestige train' experience. This antique train carriage journey normally includes a glass of champagne and a set lunch menu at the Terminal Neige refuge restaurant.
Originally the trains were pulled by steam locomotives, but these days the trains are all electric.