Ys

Ys (pronounced /ˈiːs/ EESS), also spelled Is or Kêr-Is in Breton, and Ker-Ys in French (kêr means city in Breton), is a mythical city that was built on the coast of Brittany and later swallowed by the ocean. Most versions of the legend place the city in the Douarnenez Bay.

Read more about Ys:  Development of The Legend, Adaptations in The Arts, Ys in Popular Culture