In the old days the people on Sein believed that the water from the well near the chapel could cure children from tuberculosis.
Saint Corentin (Sant Korentin, or Corentinus or Cury) died round about the year 490. He was the first Bishop of Cornouaille (Quimper), in Brittany.
He had been a recluse at Plomodiern. He visited Sein. His cult spread throughout S.W. England, where he was known as St. Cury.
His feast day is on December 12.
There's a legend on Sein that tells about Corentin miraculously changing the direction of the wind during a big storm
thus saving the island fishermen.