HANGZHOU - Chinese science ship "Xiangyanghong 10" Sunday returned to China after a voyage to the southwest Indian Ocean that lasted more than 200 days.

The ship docked at a port in Zhoushan, East China's Zhejiang Province.

The voyage was to explore the polymetallic sulphide at a seabed ore covering 30,000 square meters, under a contract signed between China and the International Seabed Authority, said Li Huaiming, a scientist involved in the project.

Scientists used China-developed unmanned submersible Qianlong 2 to conduct eight dives, reaching maximum 3,320 meters at depth. Qianlong 2 spent 170 hours, traveling 456 km for the research, proving that it was able to work on complicated terrains underwater, Li said.

Other advanced Chinese technologies in exploring polymetallic sulphide were also used, Li said.

Xiangyanghong 10 is the first Chinese ocean science survey ship built with the participation of a private company.