The Belcinac Monastery was founded in the second half of the 7th century by Saint Condède, a monk of the Abbey of Fontenelle. The monastery was built on an island in the river Seine in France, called Belcinac in ancient texts. The island, which sunk in 1330, was donated by Theuderic III. Saint Condède had built three small churches dedicated to the Blessed Virgin, Saint Peter, and Saint Valérie.
This island, located on the Seine opposite Villequier and downstream from Caudebec, was referred to as lutum (lotus) in the donation charter. The island and neighboring the Celtic houses were called "the island of Lot." In the seventh century, the island was approximately three miles long and five hundred wide and had often been partially submerged. In 1330, the island was submerged, then reappeared a few years later. However, the monastery had entirely disappeared, carried away by the waves. The island disappeared again in 1597, only to reappear in 1641. It disappeared for good in 1740, and is now lost in the wet meadows of Vatteville.