The drowning of a mythical city
Seithennyn is a character from the tale of Cantre’r Gwaelod. Cantre’r Gwaelod was a mythical city situated on a piece of land between Ynys Dewi (Ramsey Island) and Ynys Enlli (Bardsey Island). This area of land is now underwater and is known as Cardigan Bay.
The history of Cantre’r Gwaelod is illustrated in a poem in the Black Book of Carmarthen.
Seithennyn and the gates of Cantre’r Gwaelod
According to the legend, the city of Cantre’r Gwaelod was surrounded by gates to protect it from the surrounding sea. It was the responsibility of a young man named Seithennyn to close these gates every night to protect the city from flooding.
One night, a grand banquet was held at the city court, and Seithennyn drank too much mead.
In his drunkenness, he forgot to lock the gates and the sea swept in and flooded the city.
Other versions of Cantre’r Gwaelod’s tale
Other versions of Cantre’r Gwaelod’s history claim that Mererid, the daughter of the king of Cantre’r Gwaelod, caused the flood. Mererid, as well as being the princess of Cantre’r Gwaelod, was responsible for the wells. According to that story, Mererid grew angry with her situation and allowed the wells to overflow in protest.
Cantre’r Gwaelod today
They say that if you listen carefully enough on a quiet day in Aberdyfi, you can hear the bells of Cantre’r Gwaelod ringing underwater.