on the Sea side
Here is an example of itinerary proposed by Croisières Emeraude:
Departing from Bec de la vallée slip way in Dinard, 3-4 hours tour
Discovery of the river Rance estuary, the Prieuré bay, Bizeux island heading towards the Barrage de la Rance. Then sailing to the North, Saint-Servan, the old Alet City, Saint-Malo and its Forts des Bés and Fort National.
A bit further off the coast, the large Sillon beach, Fort de la Conchée and Cézembre island. It is possible to go ashore on Cézembre to see Second World War remains on a 20 min walk path way.