Juan de Nova Island (also Saint-Christophe, French: locally Île Juan de Nova or officially Île Juan da Nova) is a 4.4 km² low, flat, tropical island in the narrowest part of the Mozambique Channel, about one-third of the way between Madagascar and Mozambique at 17°03′16″S 42°43′30″E / 17.05444°S 42.725°E / -17.05444; 42.725Coordinates: 17°03′16″S 42°43′30″E / 17.05444°S 42.725°E / -17.05444; 42.725. Anchorage is possible off the northeast of the island which also has a 1,300-metre-long airstrip.

Administratively, the island is one of the Scattered islands in the Indian Ocean, a district of the French Southern and Antarctic Lands.

Juan de Nova, about six kilometres long and 1.6 km at its widest, is a nature reserve surrounded by reefs which enclose an area (not a true lagoon like in an atoll) of roughly 40 km². Forests, mainly of Casuarinaceae, cover about half the island. Large numbers of terns (Sterna fuscata) breed there from November to March. Turtles nest in the beaches around the island.

The island is named after João da Nova, a Galician admiral in the service of Portugal who came across the island in 1501. It has been a French possession since 1897. Guano (phosphate) deposits were exploited from the start of the 20th century until 1970. The island was abandoned during World War II and was visited by German submariners. Installations, including a hangar, rail lines, houses and a jetty are in ruins.

Juan de Nova, with an Exclusive Economic Zone (EEZ) of 61,050 km², is claimed by Madagascar. The island is garrisoned by French troops from Réunion and has a meteorological station (Saint-Christophe ^[1]).