)]] Ys (also spelled Is or Ker-Ys in Breton) is a mythical city built in the Douarnenez bay in Brittany by Gradlon (Gralon in Breton), King of Cornouaille, for his daughter Dahut. The legend According to the legend, Ys was built below sea level, protected from inundation by a dike. The only keys of the gate in the dam were held by Gradlon, but Satan made Dahut steal them and give them to him. He then opened the gate and Ys was flooded. In some versions of the story, Satan was sent by God to punish the city, whose inhabitants were becoming decadent. Other versions of the story tell that Dahut stole the keys either at her lover's request or in order to open the gates of the city to let her lover in. The only survivor was the King Gradlon, who was advised to abandon his daughter and Saint Winwaloe by Saint Winwaloe himself. Everyone who lived in the city died, while the souls of the dead children were then swallowed by t