Dumet Island in the Loire-Atlantique department is closed to visitors until July 31, 2024. The eight-hectare piece of land is off the coast of the town of Piriac-sur-Mer.
The island was once renowned for the nesting of large colonies of Sandwich and Common Terns. The square fort, built in 1846 to defend against the British navy, is one of the rare vestiges of its military past. The annual closure of the island could be extended until 2026, when an assessment and scientific evaluation will be carried out.