🇫🇷 France · Submerged site
Ys (Ker-Is) – Drowned Breton City
Legendary 5th c. (Gradlon of Cornouaille) – folklore recorded 19th c. · Breton / Cornish Celtic Christian syncretism (Dahut as pagan vs Christian)
Gradlon's sluice-gated city in Douarnenez Bay — daughter Dahut drowns it opening gates at high tide.