Tourists play on the beach at Dadonghai in Sanya, south China's Hainan Province, Dec. 21, 2019. As most parts of China entered the cold season of winter, Sanya becomes a hot tourist destination for tourists around the world. (Xinhua/Guo Cheng)

Kids play on the beach at Dadonghai in Sanya, south China's Hainan Province, Dec. 21, 2019. As most parts of China entered the cold season of winter, Sanya becomes a hot tourist destination for tourists around the world. (Xinhua/Guo Cheng)

Tourists experience water activities at Dadonghai in Sanya, south China's Hainan Province, Dec. 21, 2019. As most parts of China entered the cold season of winter, Sanya becomes a hot tourist destination for tourists around the world. (Xinhua/Guo Cheng)

Tourists hit the beach at Dadonghai in Sanya, south China's Hainan Province, Dec. 21, 2019. As most parts of China entered the cold season of winter, Sanya becomes a hot tourist destination for tourists around the world. (Xinhua/Guo Cheng)