
Mer de Glace (Sea of Ice) is categorized a “valley glacier”, a type of glacier that originates from mountain glaciers and flows down valleys, and located above the Chamonix valley within the Mont Blanc massif mountain range of the French Alps. Formed by the confluence of the Leschaux and Génant glaciers, the Mer de Glace is the longest and largest glacier in France, and one the biggest tourist attractions in the Chamonix valley as it’s accessible by the historic Montenvers Railway (Chemin de fer du Montenvers) and offers spectacular mountain views as well as tours, exhibits, and restaurant/hotel. However, the powerful beauty and recreational benefits of Mer de Glace were not always appreciated.
During the classical and medieval periods of European history, ice was deemed mysterious, evil and dangerous, and glaciers aroused intense fear as they were thought to be inhabited by demons that swallowed up unwary victims as well as whole villages. Consequently, glaciers were avoided, not explored, deepening myths and superstitions for many centuries. In 1690, fearful villagers of Chamonix took action against glacial evil by retaining the services of a bishop to exorcise the glaciers.
Two Englishmen on expedition to Chamonix in 1741, William Windham (1717-1761) an English landowner and Richard Pococke (1704-1765) a high ranking clergyman and anthropologist, disregarded the forewarning of evil lurking in glaciers, and climbed up the mountain for 3¾ hours with the aid of local guides and porters to carry wine (essential drink for 18th century adventure travelers) and provisions. It was a successful excursion as they returned safely and were able to provide the first written description of the glacier they called ‘Mer de Glace’. The achievement also marks the beginning of change in attitude as the phenomena of the Sea of Ice later attracted writers, adventurers, artists and photographers.

Two hundred and seventy-five years later, the explorers of Mer de Glace are on skis. In the video Ice Call from PVS Company, pro skier, Sam Favret, takes you on a freestyle tour through the icy waves, trails, and tunnels of Mer de Glace.
Vallée Blanche
Mer de Glace is certainly skiable, and you don’t have to be a ski pro like Sam Favret or an expert to enjoy the unique backcountry experience via the iconic off-piste ski route, Vallée Blanche. But, there are risks. The surface of Mer de Glace is very rough with gradient drops, large hunks of ice, deep crevasses, and seracs, making it extremely dangerous without sufficient snowfall, good intermediate skills (in all types of terrains & snow conditions) and a local mountain guide.
The Vallée Blanche is accessible from Chamonix, France via a 20 minute ride on the Aiguille du Midi cable car to the mid-station Plan de l’Aiguille (2,317m), then a walk through a tunnel and down a precarious ridge to a small, level area— the starting point for the main Vallée Blanche runs. There are four: the classic “voie normale” (the normal way), and the more challenging, Le Vrai Vallee Blanche, the Petit Envers du Plan and Grand Envers du Plan.
For the most part, the voie normale follows the valley floor through dynamic terrain, beginning with a descent into a bowl toward a large rock outcrop known as Le Gros Rognon (The Big Rock) and continuing along the mountainside. The run can be nice and smooth in spots, but depending on weather conditions, there could be deep powder, crusty layers, and icy moguls to navigate. About 2/3 down, the Refuge du Requin is a popular place to take a break, and 250 meters from there is the start of Mer de Glace. If snow conditions are good, it’s possible to ski all the way down to Chamonix. If not, the run ends at Montenvers, thus requiring a steep climb up iron stairs (misery!) to a gondola that connects to the Montenvers Railway. At a leisurely pace, including lots of stops, sightseeing and long lift queues, the up/down round trip will take 4 – 6 hours, but don’t rush…..enjoy the ride and take in the views.
The Fateful Retreat of Mer de Glace
Valley glaciers like Mer de Glace are relentlessly moving, flowing, growing, shrinking and deforming as a result of weather (temperature and snowfall) and stresses caused by the massive weight. As a result, they are appreciable indicators of climate change.
After a significant cold period in Europe during the late 19th century, Mer de Glace was so large that it reached as far as Chamonix in 1850. Today, it’s hardly visible from Chamonix as the lower end of the glacier (the ‘snout’) has been shrinking during the last 30 years at a rate of about 4-5 meters (13-16 feet) a year. There is concern the retreat will not stop as Mer de Glace is an important fresh water source for the region as well as a tourist destination, and Christian Vincent, a French glaciologist with the Laboratoire de Glaciologie et Geophysique (LGGE) and Institut de Recherche pour le Development (IRD), has warned it may shrink as much as 1.2 -1.4 kilometers (about ¾ of a mile) by the year 2040.
Resources/Information:
Wikipedia (Mer de Glace, Mont Blanc massif, Glacier, Richard Pococke, William Windham, Sr., French Alps, Chamonix, Chemin de fer du Montenvers, Aiguille du Midi, Little Ice Age)
The Annals of Mont Blanc – A Monograph by Charles Edward Mathews (1900)
Because It’s There – A Celebration of Mountaineering from 200 BC to Today (William Windham..from an Account of the Glaciers or Ice Alps in Savoy, in Two Letters) edited and translated by Alan S. Weber (2003)
Celebration of the Franco-English Friendship in Chamonix (1936), summitpost.org
Spiritual History of Ice: Romanticism, Science & Imagination by Eric G. Wilson
Chamonix visitor information: findtransfers.com (see also; chamonix.com, chamonix.net, ski-chamonix.net)
“Climate Change on Mont Blanc: The Vanishing Mer de Glace” by Helena Fouquet (2015), bloomberg.com
Mont Blanc: Glacier in Danger of Collapse, BBC News (September 25, 2019) – Italian authorities have closed roads and evacuated mountain huts after experts warned that part of a glacier on Mont Blanc could collapse.
There are more bold backcountry runs, big jumps and tricks to see on the “Downhill Runs” video channel and explore at Skiing China
Filmakers traveled to Alaska to explore Exit Glacier, but along with stunningly beautiful mountain views and amazing blue ice, they saw melting. FREE 2 WATCH → Glacier Exit
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Feature photo is a still shot from the video “Ice Call” by PVS Company
Mer de Glace photo by Detroit Publishing Co. (1890-1900), US Library of Congress Prints & Photographs, Public Domain
Chamonix Valley Map sourced from chamonix.net
Crossing the Mer de Glace on foot, photo taken about 1902-1904, Zurich Central Library, Public Domain