The only island of Lake Sainte-Croix, Costebelle Island faces the village of Salles-sur-Verdon from which it is distant of a hundred meters. It represents the emerged part of a 1,666 feet (508 meters) high hill which dominated the former village submerged under 115 feet (35 meters) of water. Sometimes accessible by ford, it is more generally reached by boat or pedal boat. It was once covered with truffle oaks which have now disappeared.