Tourists experience water activities at Wuzhizhou island in Sanya, south China's Hainan Province, Aug. 4, 2018. Sanya welcomes an increasing number of tourists since the beginning of summer vacation. (Xinhua/Guo Cheng)

Tourists experience diving at an aquarium in Sanya, south China's Hainan Province, Aug. 3, 2018. Sanya welcomes an increasing number of tourists since the beginning of summer vacation. (Xinhua/Guo Cheng)

Tourists visit an aquarium in Sanya, south China's Hainan Province, Aug. 3, 2018. Sanya welcomes an increasing number of tourists since the beginning of summer vacation. (Xinhua/Guo Cheng)

Aerial photo taken on Aug. 4, 2018 shows the scenery of Wuzhizhou island in Sanya, south China's Hainan Province. Sanya welcomes an increasing number of tourists since the beginning of summer vacation. (Xinhua/Guo Cheng)