HAIKOU -- China's scientific research ship Tansuo-2 returned to port in the city of Sanya, South China's Hainan province on Monday, after completing its ocean expedition.

The vessel carrying the 4,500-meter deep-sea manned submersible Shenhai Yongshi (Deep Sea Warrior) berthed and anchored Monday evening, according to the Institute of Deep-sea Science and Engineering of the Chinese Academy of Sciences.

As the second mother ship of China's new deep-sea manned submersible Fendouzhe (Striver), Tansuo-2 conducted several joint deep dives with Tansuo-1, another mother ship, in the Challenger Deep in the Mariana Trench, the world's deepest natural trench in the western Pacific.

Fendouzhe onboard Tansuo-1 set a national record by diving to a depth of 10,909 meters in the Mariana Trench on Nov 10.

The deep-sea video lander "Canghai," carried by Tansuo-2, realized the world's first live, real-time 4K video broadcast at a depth of 10,000 meters in sea water.

Tansuo-2 continued its scientific research mission in the Mariana Trench after completing the joint operation with Tansuo-1.

The submersible Deep Sea Warrior has successfully completed 32 deep dives during the 57-day expedition. It has set a new world record for 12 consecutive deep dives within eight days, staying in the water for an average of 8 hours and 27 minutes.

The Deep Sea Warrior has obtained a large number of videos, large organisms, in-situ micro-organisms, sediments and rock samples, accumulating valuable data for genetic research on the area and understanding its geological structure, according to the institute.