Fort National at low tide

Fort National sits on a rock a few hundred metres off the walls, built by Vauban and reachable only on foot, across the sand, when the tide is out. That is the picture: two people crossing an expanse of wet sand and seaweed-covered rock toward a small stone fort, with the walled town behind them and nothing else in the frame. On the way there are pools that hold reflections and dark rock ledges that give a foreground.

The tide is not a detail here, it is the entire plan. The range at Saint-Malo is among the largest in Europe, and the crossing opens and closes with it; people who misjudge the return spend several hours waiting on the rock. Read the tide table for the actual day, walk out on a falling tide rather than a rising one, and keep an eye on the water rather than the camera.

Bring shoes you do not mind soaking — the sand is wet and the rocks are covered in weed and barnacles — and expect everyone's feet to be grey afterwards. Dawn is the quietest and the prettiest, with the fort backlit and the sand holding colour; the same crossing at sunset gives silhouettes against the western sky.