Chinese research vessel Haiyang Dizhi-9 returns to Qingdao, Shandong province on Dec 7, 2018. [Photo provided to chinadaily.com.cn]

Chinese research ship Haiyang Dizhi-9, or Ocean Geology No 9, returned to port in Qingdao, East China's Shandong province, on Friday.

The vessel made the return after having completed a 258-day voyage.

Covering more than 25,000 nautical miles, the ship carried out geological studies in the South China Sea, gathered seismic data in the East China Sea and launched a comprehensive research project in the West Pacific Ocean, said the ship's chief scientist, Lu Kai.

"The vessel also served as a shared platform for allowing different research teams to carry out scientific research together," said Lu.

Haiyang Dizhi-9 is 87.07 meters in length, can cruise for up to 10,000 nautical miles and can reach a maximum speed over 15 knots per hour.

It is the only Chinese ship to carry out seismic, geological and geophysical study simultaneously.