Tourists attend a science exhibition held by Qingdao Underwater World in Qingdao, east China's Shandong Province, July 12, 2011. As the summer vacation begins, the sea-themed tourism programs here attract numerous visitors everyday. (Xinhua/Li Ziheng)

　　Tourists watch an underwater performance in Qingdao Underwater World in Qingdao, east China's Shandong Province, July 12, 2011. As the summer vacation begins, the sea-themed tourism programs here attract numerous visitors everyday. (Xinhua/Li Ziheng)

　　Tourists visit Qingdao Underwater World in Qingdao, east China's Shandong Province, July 12, 2011. As the summer vacation begins, the sea-themed tourism programs here attract numerous visitors everyday. (Xinhua/Li Ziheng)