Aerial views of Wanlyuyuan park in Haikou City, S China's Hainan

International students take part in a volunteer training at Fengxiang wetland park in Haikou City, south China's Hainan Province, Oct. 21, 2018. Areas along the Meishe river used to be garbage dumps. After two years' wetland restoration, the once filthy areas transformed into good places for leisure activities with powerful function of sewage purification. (Xinhua/Yang Guanyu)