Surveyors transport unmanned boat Jinghai No. 3 into water in Sanya, south China's Hainan Province, Oct. 23, 2017. China has sent two unmanned boats to join a geological survey along its 18,000 km coastline, especially in main coastal zones. Guangzhou Marine Geological Survey has introduced two unmanned boats, developed by Shanghai University, to collect data and take video, which used to be done by surveyors. (Xinhua/Zhang Jiansong)
