Gyokusendo in the Tamagusuku district. Widely known as a mysterious limestone cave, it is a prominent destination for sightseeing in Okinawa and is visited by many tourists daily. There are said to be over one million stalactites in Gyokusendo. The high temperature and humid tropical climate are a factor in the stalactites comparatively fast growth rate of one millimeter every three years, and leads to the creation of this unique underground world.