Saint-Jacut-de-la-Mer (French pronunciation: [sɛ̃ ʒaky də la mɛʁ], literally Saint-Jacut of the Sea; Breton: Sant-Yagu-an-Enez) is a commune in the Côtes-d'Armor département of Brittany in northwestern France.

The family settled in Ploufragan, where his sister Clervie (or Klervi or Creirwy) and his younger brother, Winwaloe, were born.

The monks began construction of levees (the digue des Moines) that would ensure that the land connecting Landoac to the mainland did not flood during high tides and creating the presqu'île ("almost island") of Saint-Jacut.

During the Norman invasions, the monks abandoned the abbey, retreating to the safety of southern Brittany in Saint-Jacut-les-Pins.

The monks elected their abbot, who had spiritual and temporal authority over the abbey and its extensive properties throughout Brittany and in Cambridgeshire.

A 17th-century royal order limited fishing to an official flotilla of fifteen boats manned by 120 to 180 men.

To protect the coast from foreign incursion, Louis XIV's commissioner for fortifications, Vauban, ordered the construction of a watchtower, designed by Jean-Siméon Garangeau, on the Île de Ebihens in 1694.

(The Sisters of the Immaculate Conception of Saint-Méen-le-Grand purchased the property in 1875 and constructed the current buildings, now a retreat and exhibition centre.)

Urban space replaced farms, especially to the east and south of the original village and north of the abbey, along the now-coveted seashore.