The Mer de Glace

If you’ve taken the rack railway, you’re now standing in front of one of the most iconic sights in the Mont Blanc massif: the Mer de Glace. Even though the glacier has dramatically retreated, the view is still absolutely breathtaking. In this stunning setting, you can make out the towering peaks of the massif. Just ahead are the famous Drus, with the Aiguille Verte to the right — and further left, the Grandes Jorasses.
The Mer de Glace remains France’s largest glacier. It stretches 7 kilometers long and covers 32 square kilometers — that’s about 4,500 football fields! As far back as the 18th century, European scholars and explorers were captivated by the power of this place. People said that in summer, the ice would reach right into the woods — which gave the glacier its old name: the Glacier des Bois. In 1741, two British explorers, William Windham and Richard Pococke, visited the site. They were so struck by the glacier’s size and the wave-like undulations of its surface that they gave it a new name: Mer de Glace — the Sea of Ice. This extraordinary site quickly drew the attention of scientists — including Horace-Bénédict de Saussure, who turned it into a natural laboratory for studying the mountains, making it the birthplace of modern glaciology. At the same time, the Mer de Glace became a must-see stop on the ‘Grand Tour’ — a cultural journey undertaken by young European aristocrats. During the Belle Époque, the glacier was such a sensation that people even held elegant dinners on the ice, with tables carved directly into the surface! On the technical side, this glacier is fed by several ‘arms’ of ice that descend from the high peaks at the back of the valley — Leschaux, Tacul, Talèfre… Together, they create this slow-moving river of ice that slowly flows toward Chamonix. It still moves — about 90 meters a year, carried by its own weight. But that movement merely hides a more tragic reality: the glacier is melting faster than it can rebuild. Since 1850, it has retreated more than 2.7 kilometers and lost 180 meters of thickness at the Montenvers level. It’s a bit like a moving conveyor belt — still advancing, but getting shorter all the time. The change is dramatic and clearly visible. If this isn’t your first visit, you might notice the difference yourself. If you head down to the ice cave using the walkways, you’ll see the extent of the retreat. There are now over 500 steps. At the start of the 20th century, just a few dozen were enough to reach the glacier’s surface. Along the way, you’ll see markers showing where the ice used to be — a powerful visual reminder of what’s been lost.
According to current scientific projections, the Mer de Glace could lose up to 80% of its volume by 2100 if climate trends continue. A permanent observatory is monitoring these changes, and the tiny air bubbles trapped in the ice are helping researchers uncover clues about our past climate. If you’re curious, the small Glaciorium museum nearby offers more insight into the glacier and its story. Just next to it, the historic Hôtel de Montenvers welcomes visitors in a truly exceptional setting. Built in 1880 to host early travelers drawn to the glacier, it now offers a panoramic restaurant, a cozy bar, and even a few charming rooms for those who wish to spend the night in altitude. A timeless Alpine experience, nestled between glaciers and stars. Before you leave, take a moment. Look around. You’re not just standing in front of a natural wonder — you’re witnessing a living chapter of Alpine history… and perhaps a glimpse of its future.