This underwater photo taken on July 20, 2019 shows a sea urchin taking cover amid corals at the Boundary Island Tourist Attraction in Lingshui County, south China's Hainan Province. Boundary Island in south China's Hainan Province is hosting its first series of diving-themed activities from July 19 to 21, attracting diving enthusiasts, tourists, marine ecologists and diving equipment dealers worldwide. The PADI (Professional Association of Diving Instructors) Women Dive Day event was also held here on Saturday alongside the main events. (Xinhua/Yang Guanyu)