Photo taken on June 15, 2019 shows Discovery, a remote operated vehicle aboard KEXUE, returning from the sea in western Pacific Ocean. China's research vessel KEXUE (Science) finished its investigation of seamounts in the west of the Pacific Ocean and started to sail back on Saturday evening. KEXUE is scheduled to arrive in Xiamen of China's Fujian Province on June 23. (Xinhua/Zhang Xudong)