The Cotentin Peninsula (USˌkoʊtɒ̃ˈtæ̃, kɔtɑ̃tɛ̃; Cotentîn kotɑ̃ˈtẽ), also known as the Cherbourg Peninsula, is a peninsula in Normandy that forms part of the northwest coast of France. It extends north-westward into the English Channel, towards Great Britain. To its west lie the Gulf of Saint-Malo and the Channel Islands, and to the southwest lies the peninsula of Brittany.
The peninsula lies wholly within the department of Manche, in the region of Normandy.
The Cotentin peninsula is part of the Armorican Massif (with the exception of the Plain lying in the Paris Basin) and lies between the estuary of the Vire river and Mont Saint-Michel Bay. It is divided into three areas: the headland of Cap de la Hague, the Cotentin Pass (the Plain), and the valley of the Saire River (Val de Saire). It forms the bulk of the department of Manche. Its southern part, known as "le Marais" (the Marshlands), crosses from east to west from just north west of Saint Lo and east of Lessay and marks a natural border with the rest of Manche.
The largest town on the peninsula is Cherbourg-en-Cotentin, a major cross-channel port on the north coast, with a population of approximately 120,000. The population of the peninsula is about 250,000.
The western coast of the peninsula, known as the Côte des Îles ("Islands Coast"), faces the Channel Islands. Ferry links serve Carteret and the islands of Jersey, Guernsey and Alderney from Dielette. Off the east coast of the peninsula lies the island of Tatihou and the Îles Saint-Marcouf.
The oldest stone in France is found in outcroppings on the coast of Cap de la Hague, at the tip of the peninsula.[ Bay of Écalgrain and Bay of Cul-Rond] Website "Lithothèque de Normandie"
Cotentin was almost an island at one time. Only a small strip of land in the heath of Lessay connected the peninsula with the mainland. Thanks to the so-called portes à flot (fr), which close at flood and open at ebb and which were built in the west coast and in the Baie des Veys, on the east coast, the Cotentin has become a peninsula.