Amirante Islands - Saint Joseph Atoll

Saint Joseph Atoll

Saint Joseph Atoll is located at the eastern edge of the Amirantes Bank. Depths of 500 m are found only 1.5 km east of the reef edge, and of 1000 m one kilometer further east. The atoll is roughly oval-shaped, 7 km long and 4.4 km wide. Its total area is 22.53 km², of which 11.74 km² comprises the peripheral reef flat, 4.8 km² the interior lagoon, and only 1.39 km² the land area of all islets. The lagoon is completely enclosed by the surrounding reef. At low water it drains over a narrow sill, Passe Lerein Fin, at its western end. The lagoon has a maximum depth of 6.4 m. Other soundings range from 2.1 to 3.7 m. The peripheral reefs, in addition to being exceptionally wide, are covered (except on the west side) with mobile sand. Intertidal sand sheets are encroaching on the margins of the lagoon on its windward side, which is marked for much of its extent by a discontinuous linear sandbar. There are no growing reefs in the lagoon. There was once a small settlement at the western end of St. Joseph islet, now abandoned. The tree tops are about 24 m high.

The atoll has 14 sandy islets: the three larger ones along the northeast and east shore, which are covered by coconut plantations, and the remaining ones in the south:

1. Ressource Island (third largest, northernmost)
2. Fouquet Island (ÎIe aux Fouquets) (second largest, northeast)
3. Poule Island (ÎIe aux Poules)
4. Chien Island
5. Saint Joseph Island (largest, easternmost)
6. Benjamen Island
7. Petit Carcassaye Island
8. Grand Carcassaye Island
9. Pelican Island (Pélicans)
10. ÎIe Paul
11. Bancs Ferrari
12. Banc de Sable
13. Banc aux Cocos
14. Vars

Some sources cite a smaller number of islands, because the shape especially of the smaller islets is constantly changing, with the effect that some of them merge. The Carcassaye islets, for example, actually form the southern part of St. Joseph islet.