The longest and largest glacier in France is smaller than what glacier in the Alps?
Mer de Glace: The Mer de Glace is a valley glacier located on the northern slopes of the Mont Blanc massif, in the French Alps. Mer de Glace:  It is 7.5 km long and 200 m deep but, when all its tributary glaciers are taken into account, it can be regarded as the longest and largest glacier in France, and the second longest in the Alps after the Aletsch Glacier.
i don't know