This is Fort Louvois, just off the coast and near a town which you don't want to try to pronounce - Bourcefranc-le-Chapus. It was built in the 1700s for coastal defence. This walkway was still partially submerged when we arrived there, but as the tide went out, it became clear. The funny things you see on the right are part of the oyster business in the area.

More on that as we go along.