Tatihou, Tidal island with Vauban fortification in Saint-Vaast-la-Hougue, France.

Tatihou is a 29-hectare tidal islet 1,400 metres off Saint-Vaast-la-Hougue, reached by amphibious craft or on foot at low tide. A long low stone building with a steep tiled roof and a row of small windows stands beside a massive round tower, windowless below and crenellated above, built from 1694 by Benjamin de Combes, a disciple of Vauban.

The island played a role in the Battle of La Hougue in 1692, a major naval conflict between French and English fleets. Later it served as a quarantine station for plague victims from Marseille during an epidemic in 1720.

The name Tatihou combines the Old Norse personal name Tati with the -hou suffix, explained either by Old English hōh, "rocky escarpment", or Old Norse hólmr, "islet". Since 1995 the island has hosted Les Traversées de Tatihou, a folk festival held around 15 August whose hours follow the tides so visitors can get home.

The island is accessible on foot across oyster beds at low tide or by amphibious craft, with visitor numbers limited each day. It is important to check tide times before planning a visit, as access depends heavily on tidal conditions.

The maritime museum displays the Sainte-Thérèse-Souvenez-Vous, a 1948 fishing vessel that visitors can still explore inside. This boat tells the story of local fishing traditions and how people once made their living from these waters.