Knowing nearly nothing about deep-sea manned submersibles, Ye got a vague idea about the possible contours of the vehicle by repeatedly watching Hollywood blockbuster Titanic.

The Jiaolong deep-sea submersible, with a 7,500-meter dive capacity, entered service in 2010, making China the fifth country in the world to have deep-sea exploration technology, after the United States, France, Russia and Japan. However, many of the key parts were created in foreign countries, including the metal sphere which was created in Russia.

Despite the success of Jiaolong, rather than directly develop a submersible that can reach the Mariana Trench, Chinese scientists decided to first create one using entirely domestic know-how that is capable of reaching a depth of 4,500 meters. Submersible Shenhai Yongshi was delivered to the Chinese Academy of Sciences in late 2017, conducting intensive scientific operations.

On Nov 10, 2020, Fendouzhe, carrying three people, dived to a depth of 10,909 meters in Challenger Deep, an 11,000-meter chasm located at the bottom of the Mariana Trench.

Fendouzhe was a significant improvement over its predecessors in almost every respect, including descending and ascending speeds, material toughness and battery capacity.

"But there is still big space for improvement. Now Chinese researchers are working on communication networks that can facilitate accurate positioning of submersibles in the deep sea," Gao says.