! The only stretches of water on the eastern borders of France are the river Rhine and some waterfront on the shores of Lake Geneva. The Riviera from Saint Tropez to the Italian border is sometimes known as the southeast coast of France - but not the east coast.  The only length of east-facing coast in Metropolitan France is the east side of the Cotentin peninsula, in Normandy, and the eastern shores of some islands, including the east coast of Corsica.