Juan de Nova, about 6 kilometres (3.7 mi) long and 1.6 kilometres (0.99 mi) 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 square kilometres (15 sq mi). Forests, mainly of Casuarinaceae, cover about half the island. Sea turtles nest on the beaches around the island.
The island is named after Juan de Nova, a Spanish admiral in the service of Portugal who came across the island in 1501. The island had never been inhabited when it became a possession of France in 1897. In 1921, France decided to transfer the administration of Juan de Nova from Paris to Tananarive in its colony of Madagascar and Dependencies. Before the independence of Madagascar, France transferred the administration to Saint-Pierre on Réunion Island, but Madagascar now claims the sovereignty on the island. 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.
The island lies on the sea route between South Africa and the northern tip of Madagascar. It is affected by strong currents, and has become the site of numerous wrecks. Most visible are the remains of the SS Tottenham which ran onto the southern fringing reef in 1911.