Indonesia offers many spectacular diving sites, but this one is still a secret. Sangeang volcano on the coast of Sumbawa is home to the best macro diving sites in the world. Volcanoes might have a bad reputation, but volcanic debris is quite fertile and creates life. Underwater, the debris transforms into a magical substance that hosts countless marine life and forms beautiful shapes. So, no wonder that some of the best macro diving in the world is often found around volcanic reefs.