Unmanned submersible "Hailong III" is put into the water for a deep sea testing from the Chinese research vessel Dayang Yihao (Ocean No. 1) on March 24, 2018. The submersible completed a 1690-meter-deep sea testing in west Pacific Ocean on Sunday. (Xinhua/Chen Hao)

DAYANG YIHAO, March 25 (Xinhua) -- The unmanned submersible "Hailong III" completed its first deep sea test in the western Pacific Ocean on Sunday.

The submersible entered the 1,690-meter-deep sea area from the Chinese research vessel Dayang Yihao (Ocean No. 1) at 5:20 a.m.

Chu Fengyou, chief scientist of Dayang Yihao, said the submersible, equipped with rock cutting tools and sampling manipulators, took pictures of seamount crusts and completed its tasks for the test.

"Hailong III," which is able to dive to a depth of 6,000 meters, completed a 400-meter-deep shallow sea test in the western Pacific on Saturday.

Chinese research vessel Dayang Yihao (Ocean No. 1) left Qingdao, Shandong Province, on Tuesday, taking scientists on a 45-day scientific ocean expedition. The ship is carrying advanced scientific equipment and unmanned submersibles "Hailong" and "Qianlong."