The Chapelle des Marins, also called the Chapelle Saint-Valery, sits at the highest point of the chalk cliff west of town, looking out over the entire Baie de Somme. The walk up from the upper town takes ten minutes through quiet paths shaded by trees, and the destination is worth it for the view alone — at low tide the bay spreads out as a vast sheet of pale sand veined with channels, and on a clear day you can see across to Le Crotoy on the far shore.
The chapel itself is small, a single nave of flint and brick built and rebuilt over many centuries. It is dedicated to Saint Valery, the seventh-century hermit who founded an abbey here and gave the town its name; his tomb is set into the chapel floor. Fishermen and their families have come up here for centuries to ask for safe voyages, and the walls are hung with model boats and votive plaques.