The Écomusée Picarvie is a privately run museum on the eastern edge of town, set up to preserve and present the rural and craft traditions of nineteenth-century Picardy. The collection occupies a long hall arranged as a series of reconstructed workshops and rooms: a cobbler's, a forge, a school, a kitchen, a wine merchant's. Everything is filled with the objects you would have found in it a hundred years ago, much of it donated by local families.
It's small but well done, and gives a sense of what life was like in this part of France before the bay was rediscovered by tourists. Allow about an hour. The museum has irregular opening hours outside the summer season — check before making a special trip.