Tourism has strengthened Indonesia financially. The country is made up of approximately 17,000 islands. The most important ones have managed to preserve their natural ecosystems of rainforests and mangroves as for example in Bali Java and Sumatra, the country's most famous islands. Indonesia has more than 54,000 kilometres of beautiful beaches, with the islands of Karimunjawa, Togian Banda being the best preserved thanks to their isolated location which makes them difficult to reach.