The remote operated vehicle (ROV), Discovery, prepares to dive into the sea in the south of the Mariana Trench, May 27, 2019. China's research vessel KEXUE (Science) on Monday started to explore a series of seamounts in the south of the Mariana Trench, the deepest place of the earth. The remote operated vehicle (ROV), Discovery, dived into the sea on Monday morning to collect videos, information and samples from a small seamount in the southwest of the targeted area. (Xinhua/Zhang Xudong)