Aerial photo taken on Jan. 8, 2019 shows the Chinese-built dredging vessel Tian Kun Hao sailing on the sea. Tian Kun Hao, a Chinese-built dredging vessel, which is the largest of its kind in Asia, returned to the shipyard Wednesday after completing its sea trial of nearly three months. The 140-meter-long, 27.8-meter-wide vessel can dig as deep as 35 meters under the sea floor and dredge 6,000 cubic meters per hour, according to its investor, Tianjin Dredging Co., a subsidiary of China Communication Construction Co. (Xinhua)