Xi Jinping said that the development of manned submersible Fendouzhe and its sea trial represented China's comprehensive strength in the field of marine high technology.

Fendouzhe successfully completed 13 dives, eight of which exceeded a depth of 10,000 meters in the Mariana Trench, the world's deepest natural trench in the western Pacific.

SANYA, Nov. 28 (Xinhua) -- China's new deep-sea manned submersible Fendouzhe (Striver) returned to south China's Hainan Province on Saturday morning on board the scientific research ship Tansuo-1, after completing its ocean expedition.

The mother ship Tansuo-1 berthed and anchored in Sanya at 8:30 a.m. Saturday.

President Xi Jinping on Saturday sent a letter to congratulate on the successful completion of the 10,000-meter sea trial of the manned submersible Fendouzhe and its return to port.

Xi, also general secretary of the Communist Party of China Central Committee and chairman of the Central Military Commission, extended warm congratulations and sincere greetings to scientific researchers who are committed to deep-sea equipment development and scientific studies.

He stressed that the development of manned submersible Fendouzhe and its sea trial represented China's comprehensive strength in the field of marine high technology.

During the expedition which started on Oct. 10, Fendouzhe successfully completed 13 dives, eight of which exceeded a depth of 10,000 meters in the Mariana Trench, the world's deepest natural trench in the western Pacific.

At 8:12 a.m. on Nov. 10, the manned submersible set a new national record by diving to a depth of 10,909 meters.

The expedition team overcame difficulties such as typhoons, rain and high temperatures, conducted multiple tests and obtained a batch of sediment, rock and seabed biological samples, according to the Ministry of Science and Technology.

A joint operation of Fendouzhe and the deep-sea video lander "Canghai" was also carried out during the expedition.

The successful sea trial verified the various functions and performances of the submersible as well as China's breakthroughs in deep-sea equipment and technologies. It marked China's entry into the first echelon of deep-sea scientific research and provided strong technical support for the country's subsequent deep-sea research.

The development of home-made Fendouzhe, which began in 2016, has involved nearly 1,000 scientists and researchers from about 100 research institutions, colleges and enterprises. Fendouzhe adopts a safe and powerful energy system, an advanced control system, and a positioning system. Its cabin and buoyancy materials are more pressure-resistant compared with its predecessors.

In July 2010, China's first self-developed deep-sea manned submersible, Jiaolong, reached 3,759 meters beneath the waves. It made China the fifth country, following the United States, France, Russia, and Japan, to have the technology for a submersible dive to more than 3,500 meters below sea level.

Designed to dive to a depth of 7,000 meters, Jiaolong set a diving record of 7,062 meters in the Mariana Trench in June 2012. （Xinhua）