Chinese research vessel Science waits to depart from the city of Qingdao, east China's Shandong Province, May 18, 2019. Chinese research vessel Science left the eastern city of Qingdao Saturday, on an expedition to the little-known seamounts in the Mariana Trench, the world's deepest natural trench. Researchers will study the topography, hydrology and bioecology of the western Pacific Ocean's typical seamount, said Xu Kuidong, chief scientist of the mission with the Institute of Oceanology of the Chinese Academy of Sciences. (Xinhua/Li Ziheng)