Ile du Grand Be and Fort du Petit Be

The walk across the sand

When the tide is out, a stretch of sand opens up from Bon Secours beach, below the ramparts, and you can simply walk out to the Ile du Grand Bé. There’s no bridge and no ferry — the route only exists when the sea has retreated, which is exactly what makes it feel like a small adventure. On the island, the draw is the tomb of Chateaubriand, the Saint-Malo-born Romantic writer, marked by a deliberately plain stone cross set facing the open Atlantic, just as he asked. Around it is rough grassy ground and a wide view back to the walled town. It costs nothing, takes maybe half an hour there and back, and is genuinely atmospheric.

Just beyond sits the Fort du Petit Bé, a 17th-century sea fort you can sometimes tour for around €5 when it’s open for guided visits — but it’s further out and needs more tidal margin, so treat it as a bonus, not a given.

The tide is not optional

This is the part to take seriously: check the tide table before you set off, every time. The crossing is cut off around high tide, and people genuinely get stranded for hours on the islands when they misjudge it, waiting for the water to drop again. Note the time the causeway closes, give yourself a comfortable buffer rather than cutting it fine, and watch the sea, not just the clock — it comes in faster than you expect over flat sand.

If you only have a short window, do Grand Bé and the tomb and head back well before the tide turns; save Petit Bé for a visit when there’s a long, generous low tide, because it eats into your margin. Wear shoes you don’t mind getting wet and sandy, go on a clear day for the views back to the ramparts, and combine it naturally with a lap of the city walls above.