China is pressing ahead with a project to test a deep-sea manned submersible capable of diving to 11,000 meters as it aims to set up a deep-water laboratory to conduct marine scientific research.

Yan Kai, director of the State Key Laboratory of Deep-Sea Manned Submersible at the China Ship Scientific Research Center in Jiangsu province, says the craft is scheduled to be tested in 2021.

Yan says the vehicle will be capable of diving into the world's deepest known place - the Pacific Ocean's Mariana Trench.

The sophisticated device belongs to the Jiaolong series, whose manned deep-sea explorer dived 7,062 meters in the Mariana Trench in 2012 and set a world record. It will be jointly built by research institutes and the China Shipbuilding Industry Corp, one of China's major state-owned shipbuilders.

Yan says existing submersibles can cover 99.8 percent of the world's marine area, while the 11,000-meter deep-sea vehicle will enable scientists to exploit the remaining 0.2 percent, located in several deep trenches.

However, the development of the device still presents major challenges in areas such as pressure-resistant materials, design, power supply and telecommunications.

Despite the difficulties, Yan says it is of "huge scientific value" for human beings to explore the unknown ocean world.

Yan says such breakthroughs will lay the foundation for a deep-sea research station, where underwater visits might last from several months to half a year and dozens of people could be accommodated. Existing submersibles can only work for 12 hours in a single dive and have a very limited passenger capacity.

Under the plan, the station will be mainly used for scientific purposes. Experts can conduct genetic and biological research, and explore mineral, oil and gas resources on the seabed. Using traditional fuel cells, the device will allow passengers to live and work inside for two weeks to a month.

However, Yan says, more powerful fuel cells, nuclear power and even unknown undersea energy options could supply more power in the future.

"Due to technology constraints, only the United States and Russia are capable of building high-end submersibles and deep-sea research stations, which means they have the edge to gain new knowledge about the ocean and the earth," says Dong Liwan, a shipbuilding professor at Shanghai Maritime University.

But so far no existing data indicates that their deep-water devices can reach 11,000 meters, Yan says.

Contact the writers through jingshuiyu@chinadaily.com.cn