France’s largest glacier, the glistening 200m-deep Mer de Glace (Sea of Ice) snakes 7km down on the northern side of Mont Blanc, moving up to 1cm an hour (about 90m a year). The Train du Montenvers , a picturesque, 5km-long cog railway opened in 1909, links Chamonix' Gare du Montenvers with Montenvers (1913m), from where a cable car takes you down to the glacier and the Grotte de la Mer de Glace , an ice cave whose frozen tunnels and ice sculptures change colour like mood rings.
Your ticket also gets you into the Galerie des Cristaux, glittering with crystals from the Mont Blanc massif, and the Glaciorium , which looks at the birth, life and future of glaciers.
On foot, the Mer de Glace can be reached from Plan de l’Aiguille on the Grand Balcon Nord trail . The two-hour uphill trail from Chamonix starts near the summer luge track. Traversing the crevassed glacier requires proper equipment and an experienced guide.
