China has scored many achievements in crewed deep diving in recent years. From Jiaolong (flood dragon), Shenhai Yongshi (deep-sea warrior) to Fendouzhe (striver), the maximum diving depth of crewed submersibles of China has surpassed 10,000 meters. But China's deep-sea exploration is not just about depth.

CGTN reporter Guo Meiping spoke with Ye Cong, deputy director of China Ship Scientific Research Center and chief designer of crewed deep-sea submersible Fendouzhe, about his experience under the sea and the development of crewed diving technology in the country.

The following are excerpts from the interview, which has been edited for clarity and brevity.

CGTN: You have experienced the research and development of submersibles Jiaolong (flood dragon), Shenhai Yongshi (deep-sea warrior) and Fendouzhe (striver). What role do the three submersibles play in the development of China's crewed deep diving?

Ye: China started the development of crewed deep-sea submersibles in 2000. Jiaolong serves the exploration, protection and development of seabed resources. Many parts of Jiaolong were completed through international cooperation. Jiaolong is the first crewed submersible of China, it has independent intellectual property rights registered in terms of design. It also marks the process of China's crewed deep diving from nothing to something. 

We spent eight years on the development of Shenhai Yongshi. It has realized manned deep-diving-related equipment technology in China. Many companies that used to work in aerospace or machinery "entered the sea" through the Shenhai Yongshi project. Domestic technology has been fully utilized in crewed deep diving equipment in the project.

We spent five years on the development of Fendouzhe with a very specific target, which is exploring the deepest part of the ocean – the bottom of the Mariana Trench known as Challenger Deep – and over 30 other deep-sea ecosystems around the globe with a depth of over 6,000 meters. We believe these are the areas in the ocean we know the least about. Fendouzhe has also made some breakthroughs with our own characteristics in many technical and scientific aspects, such as snorkeling speed, working time, and capability for operations under the sea. To a large extent, it can reflect the level of China's current deep-sea technology.

CGTN: What is the greatest difficulty in developing a 10,000-meter crewed submersible like Fendouzhe?

Ye: Firstly, the submersible explores the deepest part of the ocean, it needs to withstand huge pressure. So, we need to have the technology to make it light, sturdy and hermetic enough to protect the crew and equipment inside. Secondly, what we want to achieve is more than reaching the depth of 10,000 meters or entering the 10,000-meter environment. The most important thing is to be able to carry out operations in the 10,000-meter environment. Also, entering a particular deep-sea zone shouldn't be a one-time thing or an adventure. The extreme environment that Fendouzhe explores brought us challenges, including precise positioning, communication, and operation technique.

CGTN: You have participated in many diving missions as a hydronaut. Is there any memorable story?

Ye: My maximum diving depth is 10,124 meters, during the sea trial of Fendouzhe in 2020. We were in a very narrow trench with a complicated environment. When we reached the seabed, we felt the soft sediment, it was like a blanket. Not long after, we saw a cliff. There were creatures in this kind of environment. Fish can't live any deeper than 8,000 meters, but we found creatures like sea cucumbers and gammarids. The existence of these creatures in this environment was a very interesting thing.

CGTN: Where is China's current international position in crewed diving technology?

Ye: Our three submersibles are currently responsible for more than half of the international diving annually. We hope to cooperate with global peers in scientific research, making high-level scientific achievements using advanced deep-sea diving equipment. Our technology can do more than serve scientists in scientific expeditions, we can also exploit the advantages of crewed deep diving's "people on the scene" to the full in aspects of engineering, environment protection, and salvage and search. Our goal is not just the depth but more application scenarios. We are now at world-class level in terms of technology, manufacturing, testing and personnel. We are confident to serve more application scenarios.

CGTN: The 1st Deep-Sea Innovative Design Event of China is in the solicitation stage. As a judge, what role do you think this kind of event play in boosting the development of China's deep-sea technology?

Ye: Our current understanding of the ocean is mostly at the perceptual level, and our rational understanding and data about the oceans are still lacking. We want to increase understanding of the oceans through this kind of innovative event. People can reach common ground at the event and promote the development of science and art on the topic of the deep sea. We hope more people can participate, achieve breakthroughs and get inspired through the event.

Video editor: Wang Zengzheng

Cover image: Xing Cheng