The Île de Sein is a French island in the Atlantic Ocean, off Finistère, 8 kilometres from the Pointe du Raz (raz meaning "water current"), from which it is separated by the Raz de Sein. Its Breton name is Enez Sun. The island, with its neighbouring islets, forms the commune of Île-de-Sein in the Finistère department of Brittany in north-western France.
Lying on the sea routes going south from the English Channel, Sein is well known for the dangers of its waters, the Chaussée de Sein, a vast zone of reefs stretching more than thirty miles from east to west, requiring numerous lighthouses, beacons, and buoys. In the past, it was also known for its wreckers
During World War II, all the men of the island of an age to fight (variously numbered between 114 and 128), and aged from fourteen and fifty-four (or sixty according to the ile's website), embarked on their fishing boats for England where they joined Charles de Gaulle's Free French in London after hearing de Gaulle's call to resistance in his appeal to the French on 18 June 1940. In 1946, the island as a whole was admitted into the extremely select Order of the Liberation for this feat and its residents were exempted from paying income tax, a privilege they enjoy to this day.