Gyokusendo Cave in Okinawa is a hidden gem underground, offering a cool escape from the sunny beaches above. With its stunning rock formations, crystal-clear pools of water, and psychedelic light displays, this cave is a must-visit for nature lovers. Visitors can stroll along a steel walkway, marvel at the stalactites and stalagmites, and even spot cave fish swimming in the river below. For the adventurous types, there are special tours in September that take you off the beaten path, allowing you to explore the cave's restricted areas. Don't miss out on this unique underground adventure!