Okinawa is a Japanese prefecture comprising more than 150 islands in the East China Sea between Taiwan and Japan's mainland. It's known for its tropical climate, broad beaches and coral reefs, as well as its World War II sites. On the largest island (also named Okinawa) is Okinawa Peace Memorial Museum, commemorating a massive 1945 Allied invasion, and Churaumi Aquarium, home to whale sharks and manta rays.