Madagascar has world class tourism assets, and a high potential for tourism because of its biodiversity, unique wildlife, and long coastline. It is the world's fourth largest island, with almost 5,000 km (3,107 mi) of coastline and a large continental shelf equal to 20% of the island's land area. Tourism is concentrated in three areas; around the Madagascar's capital Antananarivo, and the islands of Nosy Be in the northwest and Île Sainte-Marie to the east, where beach tourism is the main tourist attraction.