Thai Prime Minister Prayut Chan-o-cha (3rd R) speaks to the rescuers in Tham Luang Khun Nam Nang Non cave in Mae Sai district of Chiang Rai, north of Thailand, on June 29, 2018. Prayut Chan-o-cha on Friday visited the flooded cave where rescuers have been searching for 12 boys and their soccer coach missing for six days and encouraged their relatives not to give up hope. (Xinhua)