Château de l'Isle-Marie is located at the heart of this nature reserve. A rich variety of flora and fauna can be observed in the protection of a 145,000-acre park which stretches all the way to the neighbouring Département du Calvados.

Thousands of years ago, the Cotentin peninsula was an island. Where the sea cut it off from the mainland, the estuaries of numerous rivers – Vire, Taute, Douve and Aure on the eastern side, and the Ay here on the west – are surrounded by a rich variety of habitat: fenland, marsh, water-meadow, estuary, pinewood, dunes and bocage, the typical Norman countryside of small fields surrounded by hedgerows and seamed with sunken roads.

There are seals in the Baie des Veys near Carentan and Isigny, and above all thousands of birds: teal, waders, oyster-catchers, curlew, buzzards, tern, storks, and migratory birds of all kinds.

Most of the park is open to visitors at all times: many nature trails and signed walks are available, and there are dozens of local centres and craft workshops. Visits can be arranged to five of the six protected areas. New observatories have just been opened overlooking the marshes at Les Ponts d’Ouve, just outside Carentan.