Ride a historic cog railway to the toe of the Mer de Glacé, France’s longest glacier, a literal “sea of ice”. View the glacier from above, then ride a cable car and walk some stairs down to an ice cave carved into the side of the glacier. Walk a path inside the glacier, you can touch the ancient ice and learn about it through informative displays. There are also more informative displays about the glacier and Mont Blanc inside the cable car station.