Competitors test the performance of their underwater robots during the 11th International Underwater Robot Competition, held in Qingdao, East China's Shandong province. [Photo provided to chinadaily.com.cn]

A referee, wearing a blue shirt, records an underwater robot's performance in the presence of audience members during the 11th International Underwater Robot Competition, held in Qingdao, East China's Shandong province. [Photo provided to chinadaily.com.cn]