China's unmanned submersible Qianlong III makes first dive into sea

China's unmanned submersible Qianlong III is retrieved from its first dive into the sea from the Chinese research vessel Dayang Yihao (Ocean No. 1), on April 20, 2018. The submersible entered the 3,955-meter-deep sea area and traveled 24.8 km. [Photo: Xinhua/Liu Shiping]