China is conducting an enormous undersea mapping and monitoring operation throughout the Pacific, Indian and Arctic oceans, constructing detailed information of marine circumstances that naval consultants say can be essential for waging submarine warfare towards america and its allies.
In a single instance, the Dong Fang Hong 3, a analysis vessel operated by Ocean College of China, spent 2024 and 2025 crusing backwards and forwards within the seas close to Taiwan and the U.S. stronghold of Guam, and round strategic stretches of the Indian Ocean, ship-tracking information reviewed by Reuters reveals. In October 2024, it checked on a set of highly effective Chinese language ocean sensors able to figuring out undersea objects close to Japan, in keeping with Ocean College, and visited the identical space once more final Could. And in March 2025, it criss-crossed the waters between Sri Lanka and Indonesia, protecting approaches to the Malacca Strait, a crucial chokepoint for maritime commerce.
In line with the college, the ship was finishing up mud surveys and local weather analysis. However a scientific paper co-written by Ocean College lecturers reveals it has additionally carried out in depth deep-sea mapping. Naval-warfare consultants and U.S. Navy officers say the kind of deep-sea information being collected by the Dong Fang Hong 3 – through mapping and placement of sensors within the ocean – is giving China an image of the subsea circumstances it could have to deploy its submarines extra successfully and seek out these of its adversaries.
The Dong Fang Hong 3 isn’t working alone. It’s a part of a broader ocean mapping and monitoring operation involving dozens of analysis vessels and lots of of sensors. In tracing this effort, Reuters examined Chinese language authorities and college data, together with journal articles and scientific research, and analysed greater than 5 years of motion by 42 analysis vessels energetic within the Pacific, Indian or Arctic oceans utilizing a ship-tracking platform constructed by New Zealand firm Starboard Maritime Intelligence.
Whereas the analysis has civilian functions – among the surveying covers fishing grounds or areas the place China has mineral prospecting contracts – it additionally serves a army one, in keeping with 9 naval-warfare consultants who reviewed Reuters’ findings.
To assemble details about underwater terrain, analysis vessels map the ocean ground whereas touring backwards and forwards in tight strains. The monitoring information reveals that sort of motion by the vessels Reuters tracked throughout giant sections of the Pacific, Indian and Arctic oceans.
At the very least eight of the vessels Reuters tracked have carried out seabed mapping, whereas one other 10 have carried gear used for mapping, in keeping with a evaluation of Chinese language state media articles, vessel descriptions revealed by Chinese language universities, and press releases by authorities organisations.
The vessels’ survey information “can be probably invaluable in preparation of the battlespace” for Chinese language submarines, mentioned Peter Scott, a former chief of Australia’s submarine drive. “Any army submariner price his salt will put quite a lot of effort into understanding the setting he’s working in.”
The ship-tracking information present that China’s seabed-surveying effort is concentrated partially on militarily essential waters across the Philippines, close to Guam and Hawaii, and close to U.S. army services on Wake atoll within the north Pacific. “The size of what they’re doing is about extra than simply sources,” mentioned Jennifer Parker, an adjunct professor of protection and safety on the College of Western Australia and former Australian anti-submarine warfare officer. “When you take a look at the sheer extent of it, it’s very clear that they intend to have an expeditionary blue-water naval functionality that is also constructed round submarine operations.”
Furthermore, Parker and different consultants added, even the place information is gathered for scientific functions, the mixing of civilian scientific analysis and army expertise growth has change into a key focus of the Chinese language authorities underneath President Xi Jinping. Beijing refers to this method as “civil-military fusion.”
China’s ministries of protection, international affairs and pure sources didn’t reply to requests for remark concerning the seabed mapping and ocean-monitoring actions. The U.S. Protection Division didn’t reply to questions from Reuters.
In testimony to a congressional fee this month, Rear Admiral Mike Brookes, the commander of the U.S. Workplace of Naval Intelligence, mentioned China had dramatically expanded its surveying efforts, offering information that “allows submarine navigation, concealment, and positioning of seabed sensors or weapons.” He added that “potential army intelligence assortment” by Chinese language analysis vessels “represents a strategic concern.”
America lately overhauled its personal efforts to map and monitor the ocean, but it surely usually does so with army vessels which might be allowed to show off the monitoring system monitored by civilian software program. China’s civilian survey ships additionally generally disable monitoring, that means its marketing campaign might go additional than Reuters may decide.
That is the primary time the extent of China’s mapping and monitoring throughout the Pacific, Indian and Arctic oceans has been reported. Earlier reporting has revealed a portion of the hassle round Guam and Taiwan, and in elements of the Indian Ocean. “It’s frankly astonishing to see the large scale of Chinese language marine scientific analysis,” mentioned Ryan Martinson, an affiliate professor specializing in Chinese language maritime technique on the U.S. Naval Warfare School.
“For many years, the U.S. Navy may assume an uneven benefit in its information of the ocean battlespace,” added Mr. Martinson. China’s efforts “threaten to erode that benefit. It’s clearly deeply regarding.”
Paranoid about being boxed in
The information that Chinese language analysis vessels are accumulating concerning the seabed and water circumstances is crucial to submarine operations and anti-submarine warfare, in keeping with naval consultants. Most clearly, mentioned Australian protection scholar Parker, commanders want details about underwater terrain to keep away from collisions and conceal their vessels. However that information can be important for detecting submarines, which function inside just a few hundred meters of the floor.
Usually, submarines are recognized by way of the sounds they emit or echoes from alerts despatched by sonar methods. Tom Shugart, a former U.S. submarine commander who’s now an adjunct senior fellow on the Heart for a New American Safety, mentioned the motion of these sound waves modifications relying on the underwater panorama.
Sound waves and submarine actions are additionally affected by water temperature, salinity and currents. The vessels concerned belong to Chinese language state entities just like the Ministry of Pure Sources or state-affiliated analysis establishments like Ocean College, whose president in 2021 publicly celebrated its “shut ties” to China’s navy and dedication to “the development of a maritime energy and nationwide protection.” The college didn’t reply to a request for remark.
China has executed its most complete ocean surveying east of the Philippines, which sits alongside the First Island Chain, the string of territories largely managed by America’s allies that runs from the Japanese islands within the north by way of Taiwan and on to Borneo within the south. The chain varieties a pure barrier between China’s coastal seas and the Pacific. “They’re paranoid about being boxed in to the First Island Chain,” mentioned Peter Leavy, previously Australia’s naval attache to the U.S. and now president of the Australian Naval Institute.
China’s mapping “signifies a want to know the maritime area to allow them to escape.” The monitoring information reveals that China’s mapping additionally covers waters surrounding Guam – the place some American nuclear submarines are stationed.
Strikingly, Chinese language vessels have additionally mapped waters round Hawaii, one in all America’s different regional army hubs; examined an underwater ridge north of a naval base in Papua New Guinea to which the U.S. lately gained entry; and scouted round Christmas Island, an Australian territory on a route between the South China Sea and a significant Australian submarine base.
China’s efforts lengthen additional. It has mapped giant swaths of the Indian Ocean, a crucial route for Chinese language imports of oil and different sources from the West Asia and Africa. “China has some key vulnerabilities in the case of dependencies on maritime commerce,” mentioned Mr. Parker, the previous anti-submarine warfare officer. The surveying “signifies that they’ll seemingly be conducting extra submarine operations within the Indian Ocean.”
China’s vessels have additionally mapped the seabed west and north of Alaska, an important sea route into the Arctic. Beijing has recognized the Arctic as a strategic frontier and declared its ambition to change into a polar nice energy by the 2030s. The in depth surveying and Beijing’s rising undersea functionality are “symptomatic of China’s rise as a premier maritime energy,” mentioned Mr. Shugart, the previous submarine commander.
A clear ocean
Round 2014, Wu Lixin, a scientist at Ocean College, proposed an bold effort to create a “clear ocean” by deploying sensors that may give China a complete view of water circumstances and motion by way of particular areas, in keeping with an announcement revealed by the state-affiliated Chinese language Academy of Sciences. The proposal shortly obtained at the least $85 million in help from the Shandong provincial authorities, in keeping with feedback by Shandong officers.
The undertaking started within the South China Sea, the place Ocean College public statements boast it has now constructed an commentary system protecting the deep-sea basin. Mr. Brookes, the director of the U.S. Workplace of Naval Intelligence, informed the congressional fee that China is constructing undersea surveillance networks that “collect hydrographic information – water temperature, salinity, currents – to optimise sonar efficiency and allow persistent surveillance of submarines transiting crucial waterways just like the South China Sea.”
After surveying the South China Sea, Chinese language scientists expanded the clear ocean undertaking to the Pacific and Indian oceans. Within the Pacific, data from the Chinese language Ministry of Pure Sources, Ocean College and the Shandong authorities present that China has deployed lots of of sensors, buoys and subsea arrays to detect modifications in water circumstances like temperature, salinity and subsea motion by way of the ocean east of Japan, east of the Philippines, and round Guam.
Within the Indian Ocean, paperwork from the Chinese language Academy of Sciences and Ministry of Pure Sources describe a sensor array ringing India and Sri Lanka, together with alongside an underwater mountain vary referred to as Ninety East Ridge. The ridge – which Chinese language vessels have additionally combed, in keeping with the Starboard information – is likely one of the world’s longest undersea mountain ranges and sits astride the method to the strategically important Malacca Strait, by way of which a lot of China’s oil provide passes.
Ocean College and the Institute of Oceanology, which is a part of the Chinese language Academy of Sciences, have mentioned the broader community of sensors now supplies China with real-time information about water circumstances and subsea actions. Some naval-warfare consultants expressed warning about that declare, given technical challenges with real-time communication of knowledge from underwater. However even delayed information is effective, Mr. Parker mentioned, because it may assist China detect U.S. submarine operations.
Many sensors are positioned in delicate areas. For instance, Reuters lately reported on a U.S. effort to fortify a key strait between Taiwan and the Philippines to chop off Chinese language entry to the Pacific. Ocean College research present that China has deployed superior sensors in elements of the strait by way of which U.S. submarines would transfer to achieve the South China Sea. Chinese language scientists say these sensors monitor modifications in local weather and ocean circumstances. However in 2017, authorities officers from Shandong province mentioned the clear ocean undertaking was meant to “guarantee maritime protection and safety” and explicitly in contrast the undertaking with a U.S. army effort to construct an American ocean-sensor community.
Shandong’s authorities, the Chinese language Academy of Sciences and the Institute of Oceanology didn’t reply to requests for remark.
Mapping-program founder Wu now oversees the community by way of the Qingdao Nationwide Laboratory for Marine Science and Know-how, whose companions embody China’s Naval Submarine Academy, in keeping with the academy’s web site. Wu didn’t reply to Reuters questions.
New forms of fight capabilities
Collectively, China’s mapping and monitoring give it refined instruments to detect rival submarines and deploy its personal in among the world’s most contested waters. “It is a manifestation of China’s far-seas attain,” mentioned Collin Koh, a senior fellow in maritime safety at Singapore’s RSIS Institute of Defence and Strategic Research. “They now have a fairly good image of the maritime area they hope to function in, both in peacetime or in warfare.” Chinese language researchers, equally, see strategic worth of their work. Zhou Chun, an Ocean College researcher who oversees the Indian and Pacific ocean sensor arrays, was quoted final yr in an Ocean College press launch as saying that his work had proven him “the speedy growth of my nation’s maritime protection and army capabilities.” He didn’t reply to Reuters questions.
Going ahead, Mr. Zhou pledged to “remodel probably the most advance dscientific and technological achievements into new forms of fight capabilities for our army at sea.”