It's one of France's most iconic images: the slender towers and sky-scraping turrets of the abbey of Mont St-Michel rising from stout ramparts and battlements, the whole ensemble connected to the mainland by a narrow causeway (which will be replaced by a bridge by 2014; see www.projetmontsaintmichel.fr for more information on the changes that are under way). Fortunately, although it's visited by huge numbers of tourists, both French and foreign, the Mont still manages to whisk you back to the Middle Ages, its fantastic architecture set against the backdrop of the area's extraordinary tides.
The bay around Mont St-Michel is famed for having Europe's highest tidal variations; the difference between low and high tides can reach an astonishing 15m. The Mont is only completely surrounded by the sea every month or two, when the tidal coefficient is above 100 and high tide is above 14m. Regardless of the time of year, the waters sweep in at an astonishing clip, said to be as fast as a galloping horse. At low tide the Mont is surrounded by bare sand for kilometres around, but at high tide, barely six hours later, the whole bay can be submerged.
Be prepared for lots of steps, some of them spiral – alas, the Mont is one of the least wheelchair-accessible sites in France. Be prepared also for big crowds; come early in the morning to miss the worst of them, though the Mont is never entirely free of visitors.