Beneath the vast, often-unseen expanses of the Pacific, Indian, and Arctic oceans, China is orchestrating a sophisticated and expansive operation to meticulously map and monitor the marine environment. This endeavor, far exceeding routine scientific inquiry, is forging a comprehensive understanding of undersea conditions that naval strategists assert would be indispensable for China’s submarine warfare capabilities, particularly in any potential confrontation with the United States and its allies.
One illustrative example of this ambitious undertaking involves the Dong Fang Hong 3, a research vessel operated by the Ocean University of China. Ship-tracking data, meticulously reviewed, reveals that this vessel dedicated significant time during 2024 and 2025 to traversing strategic maritime zones. Its voyages took it repeatedly through the waters surrounding Taiwan, a region of immense geopolitical sensitivity, and in the vicinity of Guam, a critical U.S. military bastion. Furthermore, its operational theater extended to key sectors of the Indian Ocean. In October 2024, the Dong Fang Hong 3 actively engaged with a network of powerful Chinese ocean sensors designed to detect and identify undersea objects, a mission it revisited in the same Japanese-adjacent waters in May of the following year. March 2025 saw the vessel charting a course across the waters between Sri Lanka and Indonesia, strategically covering vital approaches to the Malacca Strait, a global chokepoint for maritime commerce and resource flow.
While the Ocean University of China officially describes the Dong Fang Hong 3’s activities as focused on “mud surveys and climate research,” a deeper analysis of academic publications co-authored by university researchers paints a more complex picture. These papers detail extensive deep-sea mapping initiatives undertaken by the vessel. Naval warfare experts and U.S. Navy officials, examining the nature of the data being collected – through both advanced mapping techniques and the strategic placement of sensors – contend that China is acquiring precisely the kind of subsea environmental intelligence necessary to enhance the operational effectiveness of its own submarines and to more effectively locate and track adversary submarines.
The Dong Fang Hong 3 is not an isolated actor in this grand design. It is an integral component of a much broader, coordinated effort encompassing dozens of research vessels and hundreds of sophisticated sensors deployed across the world’s oceans. In tracing the scope and ambition of this operation, a comprehensive review of Chinese government and university records, including scientific journals and research studies, was undertaken. This was complemented by an analysis of over five years of movement data for 42 research vessels actively operating in the Pacific, Indian, and Arctic oceans, utilizing a specialized ship-tracking platform developed by the New Zealand company Starboard Maritime Intelligence.
While acknowledging the legitimate civilian applications of such research – including surveying fishing grounds and areas where China holds mineral prospecting contracts – the overwhelming consensus among nine naval warfare experts who reviewed the findings is that these activities serve a significant military purpose. The meticulous process of gathering information about the underwater terrain involves research vessels systematically mapping the seabed by traveling back and forth in precise, grid-like patterns. The analyzed ship-tracking data clearly demonstrates this characteristic movement across vast swathes of the Pacific, Indian, and Arctic oceans by the vessels under scrutiny.
A review of Chinese state media articles, official vessel descriptions published by Chinese universities, and press releases from government organizations indicates that at least eight of the tracked vessels have been actively engaged in seabed mapping. An additional ten vessels have been observed carrying equipment specifically designed for such mapping operations. This concerted effort to chart the ocean floor is viewed by experts as a critical precursor to naval operations.
“The survey data these vessels are collecting would be potentially invaluable in preparing the battlespace,” stated Peter Scott, a former chief of Australia’s submarine force. He elaborated, “Any military submariner worth his salt will put a great deal of effort into understanding the environment he’s operating in.” This underscores the fundamental principle that detailed environmental intelligence is a cornerstone of effective submarine warfare.
The ship-tracking data highlights a strategic focus in China’s seabed surveying efforts on waters of significant military importance. These include the maritime zones around the Philippines, a crucial component of the First Island Chain; the waters near Guam and Hawaii, both major U.S. military hubs; and areas proximate to U.S. military installations on Wake Atoll in the North Pacific. This geographical concentration suggests a deliberate effort to gain an advantage in regions critical to regional security dynamics.
“The scale of what they’re doing is about more than just resources,” observed Jennifer Parker, an adjunct professor of defense and security at the University of Western Australia and a former Australian anti-submarine warfare officer. She emphasized, “If you look at the sheer extent of it, it’s very clear that they intend to have an expeditionary blue-water naval capability that also is built around submarine operations.” This points to a long-term strategic vision for China’s naval power projection.
Furthermore, Parker and other analysts highlight that even when data is collected under the guise of scientific research, the Chinese government, under President Xi Jinping, has made the integration of civilian scientific endeavors with military technology development a central tenet of its national strategy. This overarching approach is officially termed “civil-military fusion,” signifying a deliberate blurring of lines between civilian and military objectives.
In response to inquiries regarding these extensive seabed mapping and ocean-monitoring activities, China’s ministries of defense, foreign affairs, and natural resources did not provide comment. Similarly, the U.S. Department of Defense declined to respond to questions posed by Reuters.
Adding significant weight to these concerns, Rear Admiral Mike Brookes, the commander of the U.S. Office of Naval Intelligence, testified before a congressional commission this month. He stated that China has dramatically escalated its surveying efforts, generating data that “enables submarine navigation, concealment, and positioning of seabed sensors or weapons.” He further characterized the “potential military intelligence collection” by Chinese research vessels as a “strategic concern.”
While the United States has recently undertaken its own initiatives to map and monitor the oceans, it typically employs military vessels equipped with tracking systems that can be deactivated for civilian monitoring software. The Chinese civilian survey ships, like their military counterparts, also occasionally disable their tracking systems, suggesting that the full extent of their campaign may be even broader than what the publicly available data can reveal.
This comprehensive report marks the first time the full scope of China’s ocean mapping and monitoring operations across the Pacific, Indian, and Arctic oceans has been publicly detailed. Previous reporting had shed light on portions of this effort, particularly around Guam and Taiwan, and in select areas of the Indian Ocean, but this analysis provides an unprecedented overview of its vast geographical reach and strategic implications.
“It is frankly astonishing to see the enormous scale of Chinese marine scientific research,” remarked Ryan Martinson, an associate professor specializing in Chinese maritime strategy at the U.S. Naval War College. He added a stark assessment of the implications: “For decades, the U.S. Navy could assume an asymmetric advantage in its knowledge of the ocean battlespace. China’s efforts threaten to erode that advantage. It is obviously deeply concerning.”
‘Paranoid About Being Boxed In’
The granular data that Chinese research vessels are systematically collecting on seabed topography and water conditions is, according to naval experts, absolutely critical for effective submarine operations and anti-submarine warfare. As Australian defense scholar Parker explained, a fundamental requirement for submarine commanders is detailed knowledge of the underwater terrain to prevent collisions and to effectively conceal their vessels. This is the most obvious application of such mapping data.
However, the utility of this data extends far beyond simple navigation and concealment. It is equally essential for the detection of submarines, which typically operate within a few hundred meters of the surface. The primary methods for identifying submarines involve analyzing the sounds they emit or interpreting echoes from active sonar systems. Tom Shugart, a former U.S. submarine commander and now an adjunct senior fellow at the Center for a New American Security, elaborated on this point, explaining that the propagation of sound waves through water is significantly influenced by the underwater landscape. Variations in the seabed, water depth, and underwater structures can alter the path and characteristics of sonar signals, thereby affecting a submarine’s detectability.
Beyond the physical terrain, sound waves and submarine movements are also profoundly affected by a complex interplay of factors including water temperature, salinity, and ocean currents. These environmental variables can create “shadow zones” or, conversely, amplify acoustic signals, creating challenging conditions for both operating submarines and those attempting to detect them. Comprehensive mapping of these dynamic oceanographic features is therefore crucial for optimizing sonar performance and for understanding the acoustic environment.
The research vessels involved in this extensive survey effort belong to prominent Chinese state entities, including the Ministry of Natural Resources and state-affiliated research institutions such as the Ocean University of China. The president of Ocean University, in a public statement in 2021, proudly highlighted the university’s “close ties” to China’s navy and its unwavering commitment to “the construction of a maritime power and national defense.” The university did not respond to a request for further comment on these connections.
China’s most comprehensive ocean surveying activities have been concentrated east of the Philippines. This region lies along the First Island Chain, a strategic arc of territories largely controlled by America’s allies, stretching from the Japanese islands in the north, through Taiwan, and down to Borneo in the south. This chain of islands and maritime territories forms a significant natural barrier, effectively delineating China’s coastal seas from the vast expanse of the Pacific Ocean.
“They’re paranoid about being boxed in to the First Island Chain,” observed Peter Leavy, formerly Australia’s naval attaché to the U.S. and now president of the Australian Naval Institute. He interpreted China’s extensive mapping efforts as a clear indication of a “desire to understand the maritime domain so they can break out.” This suggests a strategic imperative for China to overcome geographical constraints and project its naval power further into the open ocean.
The ship-tracking data reveals that China’s mapping activities also encompass the waters surrounding Guam, a key strategic location where several American nuclear submarines are stationed. The detailed charting of these waters would provide crucial intelligence for potential anti-submarine operations or for planning offensive submarine missions.
In a particularly striking development, Chinese vessels have also meticulously mapped waters in the vicinity of Hawaii, another vital U.S. regional military hub. Furthermore, they have investigated an underwater ridge located north of a naval base in Papua New Guinea, a facility to which the U.S. has recently gained access, suggesting an interest in strategic chokepoints and potential basing locations. Additionally, Chinese vessels have been scouting around Christmas Island, an Australian territory situated on a critical sea lane connecting the South China Sea to a vital Australian submarine base, indicating a broad interest in maritime access and control.
China’s ambitious surveying extends significantly into the Indian Ocean, a region of immense strategic and economic importance. Vessels have meticulously mapped large swathes of this ocean, which serves as a critical artery for China’s imports of oil and other essential resources from the Middle East and Africa. The detailed mapping of this area is likely intended to enhance China’s ability to protect its maritime trade routes and to conduct naval operations in support of its global interests.
“China has some key vulnerabilities when it comes to dependencies on maritime trade,” noted Parker, the former anti-submarine warfare officer. She concluded that the extensive surveying in the Indian Ocean “indicates that they will likely be conducting more submarine operations in the Indian Ocean.” This suggests a growing emphasis on undersea power projection in a region vital to China’s economic lifeline.
The scope of China’s underwater mapping also includes the seabed west and north of Alaska, an increasingly important sea route into the Arctic. Beijing has identified the Arctic as a strategic frontier and has openly declared its ambition to become a major polar power by the 2030s. The comprehensive mapping of this region is crucial for understanding its unique environmental conditions and for planning future maritime activities, including resource extraction and naval deployments.
The extensive surveying operations, coupled with China’s rapidly developing undersea capabilities, are “symptomatic of China’s rise as a premier maritime power,” asserted Shugart, the former submarine commander. This growth in oceanic intelligence and capability signifies a fundamental shift in the global balance of naval power.
A ‘Transparent Ocean’
Around 2014, Wu Lixin, a scientist at the Ocean University of China, proposed an ambitious initiative aimed at creating a “transparent ocean.” The core concept involved deploying a dense network of sensors capable of providing China with a comprehensive and real-time view of water conditions and undersea movements within specific operational areas. According to a statement published by the state-affiliated Chinese Academy of Sciences, this visionary proposal quickly garnered significant financial backing, receiving at least $85 million in support from the Shandong provincial government, as confirmed by comments made by Shandong officials.
The initial phase of this ambitious “transparent ocean” project commenced in the South China Sea. Public statements released by the Ocean University of China proudly boast that the university has since established a sophisticated observation system that now effectively covers the entire deep-sea basin of this strategically vital waterway. This suggests a successful implementation of the sensor network concept in a critical maritime environment.
Rear Admiral Mike Brookes, the director of the U.S. Office of Naval Intelligence, further elaborated on the strategic implications of China’s efforts in his testimony to the congressional commission. He stated that China is actively constructing advanced undersea surveillance networks designed to “gather hydrographic data – water temperature, salinity, currents – to optimize sonar performance and enable persistent surveillance of submarines transiting critical waterways like the South China Sea.” This highlights the dual-use nature of the data being collected, serving both scientific and military objectives.
Following the successful implementation of the “transparent ocean” project in the South China Sea, Chinese scientists have systematically expanded its reach into the Pacific and Indian oceans. Records originating from the Chinese Ministry of Natural Resources, the Ocean University of China, and the Shandong provincial government reveal that China has deployed hundreds of interconnected sensors, buoys, and subsea arrays. These instruments are designed to detect subtle changes in water conditions, such as temperature and salinity, as well as to monitor subsea movements across vast oceanic regions. Key areas of deployment include waters east of Japan, east of the Philippines, and around Guam, indicating a strategic focus on regions with significant naval activity.
In the Indian Ocean, documents sourced from the Chinese Academy of Sciences and the Ministry of Natural Resources describe an extensive sensor array strategically positioned to encircle India and Sri Lanka. This network notably includes installations along a prominent underwater mountain range known as the Ninety East Ridge. Chinese vessels have also been observed extensively surveying this ridge, according to the Starboard data. The Ninety East Ridge, one of the world’s longest undersea mountain ranges, is situated directly along the primary approach to the strategically indispensable Malacca Strait, through which a substantial portion of China’s oil supply transits. The comprehensive monitoring of this area is clearly aimed at securing vital energy routes.
Both the Ocean University of China and the Institute of Oceanology, a key component of the Chinese Academy of Sciences, have publicly stated that this expansive network of sensors now provides China with real-time data concerning water conditions and subsea movements. This capability, if fully realized, would represent a significant advancement in China’s maritime intelligence gathering.
While some naval warfare experts express a degree of caution regarding the claim of true real-time data transmission from underwater environments, acknowledging the inherent technical challenges involved, they concur that even delayed data holds substantial strategic value. As Parker pointed out, such data, even with a time lag, could be instrumental in detecting U.S. submarine operations. This underscores the persistent intelligence advantage that environmental data provides.
The placement of many of these advanced sensors is in highly sensitive geographical locations. For instance, in a recent report, Reuters detailed a U.S. effort to fortify a key strait between Taiwan and the Philippines, a move intended to impede Chinese access to the Pacific Ocean. Intriguingly, studies conducted by the Ocean University of China indicate that China has strategically deployed advanced sensors within parts of this very strait, through which U.S. submarines would likely transit to reach the South China Sea. This suggests a deliberate counter-strategy and an effort to monitor opposing naval movements.
Chinese scientists maintain that these sensors are primarily tasked with monitoring changes in climate and oceanographic conditions. However, in 2017, government officials from Shandong province explicitly stated that the “transparent ocean” project was designed to “ensure maritime defense and security.” Furthermore, they directly compared the project’s objectives with a U.S. military initiative aimed at building a comprehensive American ocean-sensor network, clearly signaling a competitive and strategic motivation behind China’s endeavors.
The Shandong provincial government, the Chinese Academy of Sciences, and the Institute of Oceanology did not respond to requests for comment on these statements and projects.
Wu Lixin, the architect of the “transparent ocean” mapping program, now oversees the sprawling sensor network through the Qingdao National Laboratory for Marine Science and Technology. According to the official website of China’s Naval Submarine Academy, this laboratory lists the academy as one of its key partners. This direct link to a primary military branch further underscores the defense-oriented implications of the research. Wu Lixin himself did not respond to Reuters’ inquiries.
‘New Types of Combat Capabilities’
Taken together, China’s extensive ocean mapping and its sophisticated monitoring network provide the People’s Liberation Army Navy (PLAN) with powerful tools to detect rival submarines and to deploy its own submarines with enhanced effectiveness in some of the world’s most strategically contested maritime zones. This integrated approach represents a significant leap forward in China’s naval capabilities.
“This is a manifestation of China’s far-seas reach,” observed Collin Koh, a senior fellow in maritime security at Singapore’s RSIS Institute of Defence and Strategic Studies. He elaborated, “They now have a reasonably good picture of the maritime domain they hope to operate in, either in peacetime or in war.” This implies a readiness and capability for sustained naval operations beyond China’s immediate littoral waters.
Chinese researchers themselves recognize the profound strategic value of their work. Zhou Chun, a researcher at Ocean University who oversees the sensor arrays in the Indian and Pacific oceans, was quoted in an Ocean University press release last year as stating that his work had afforded him a firsthand view of “the rapid development of my country’s maritime defense and military capabilities.” Zhou Chun did not respond to Reuters’ questions regarding his research and its implications.
Looking ahead, Zhou pledged a commitment to “transform the most advanced scientific and technological achievements into new types of combat capabilities for our military at sea.” This forward-looking statement explicitly links scientific advancement to the development of tangible military power, highlighting the strategic direction of China’s maritime research and development efforts.
