How do I get to Mont Saint-Michel?
You have to take the train to Rennes at Montparnasse train station. The train takes about two and a half hours. About 1 hour and 20 minutes by bus from the bus stop in front of Rennes Station.
There are often free shuttle buses to Mont Saint Michel near the Information Center. Shuttle buses usually run every 5 to 10 minutes.
Mont Saint-Michel is 364 km away from Paris, so I recommend a two-day schedule.