The Archipelago of the Chausey Islands includes a multitude of islets, some immersed at high tide. The landscape and the light change depending on the time. The archipelago is an ornithological reserve where many seabirds such as herring gulls, cormorants, or turnstones come to nest and, for some, to winter. The entire area joining the Baie du Mont-Saint-Michel to the mouth of the Sienna is listed as a protected area.