Crew members of Tansuo-2, the second mother ship of China's new deep-sea manned submersible Fendouzhe (Striver), disembark from the vessel with their relatives who are here to greet them in Sanya, south China's Hainan Province, Dec. 21, 2020. China's scientific research ship Tansuo-2 returned to port in the city of Sanya, south China's Hainan Province on Monday, after completing its ocean expedition. (Xinhua/Zhao Yingquan)