Fodor's Expert Review Lac Souterrain St-Léonard

For an activity the whole family can enjoy, take a half-hour boat ride across the largest natural subterranean lake in Europe at 984 feet long, where you can see strange rock formations and even fish under the crystal clear water. Bring an extra sweater, even in summer, as it gets chilly when you descend into the cave. Watch for monthly boat concerts on the lake, where the acoustics are exceptional.