The Chaussée de Sein (Sein Causeway)
At the western extremity of the island, the visitor can see part of the
Causeway, a 25-km underwater "street" cobbled with rocks and cliffs. Here,
the lucky visitor will be able to view dolphins and seals in certain
seasons. The most famous lighthouse of the island is Ar Men, hardly visible
here, which signals the beginning of the Causeway. It took thirteen years
to build and complete.