China is conducting one of the most extensive ocean-mapping campaigns in modern history, deploying dozens of research vessels to chart the sea floor and monitor underwater conditions in strategically critical regions. While some of the work focuses on civilian objectives like mineral exploration and fishing grounds, naval experts tell Reuters that the data being gathered is equally vital for military planning, giving Beijing a detailed picture of the maritime environment needed to conduct submarine warfare against the United States and its allies.
The Dong Fang Hong 3, operated by the Ocean University of China, spent 2024 and 2025 crisscrossing waters near Taiwan, Guam, and key stretches of the Indian Ocean, including approaches to the Malacca Strait, according to ship-tracking data reviewed by Reuters. The vessel conducted mud surveys and climate research, but Ocean University publications and co-authored scientific papers show that it also engaged in extensive deep-sea mapping. U.S. Navy officials and naval-warfare analysts note that such surveys provide crucial intelligence on seabed topography, underwater currents, and other factors that could determine the success of submarine operations and anti-submarine warfare.
The Dong Fang Hong 3 is just one element of a massive Chinese effort involving 42 research vessels tracked over five years and hundreds of sensors deployed across the Pacific, Indian, and Arctic oceans. Tracking patterns reveal vessels repeatedly surveying key maritime chokepoints and areas surrounding U.S. bases, including Guam, Hawaii, and Wake Atoll. Experts warn that these surveys could allow China to conceal its submarines, detect adversary submarines more effectively, and optimize the positioning of seabed sensors or undersea weapons.
Jennifer Parker, a former Australian anti-submarine warfare officer and adjunct professor at the University of Western Australia, said, “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.” Other analysts emphasize the integration of civilian scientific work and military objectives, a hallmark of Beijing’s “civil-military fusion” strategy under President Xi Jinping, which seeks to convert technological and research advances into combat advantages.
Chinese vessels have focused their mapping on militarily sensitive areas, including waters east of the Philippines along the First Island Chain—a strategic barrier formed by U.S. allies—and surrounding Guam, Hawaii, and Papua New Guinea. Mapping activity also extends across the Indian Ocean, a crucial corridor for Chinese oil and trade, and into Arctic waters north and west of Alaska, reflecting Beijing’s ambition to become a polar power by the 2030s. U.S. and Australian experts note that this pattern indicates China’s desire to avoid being “boxed in” by regional chokepoints and to ensure freedom of movement for its submarine fleet in any potential conflict.
The Ocean University’s “Transparent Ocean” initiative, launched in the South China Sea and expanded across the Pacific and Indian oceans, deploys sensors and observation arrays to collect detailed data on temperature, salinity, currents, and subsea activity. The program, initially funded with $85 million from Shandong provincial authorities, provides China with a growing undersea intelligence network. While the Chinese government frames the project as supporting scientific research, officials have explicitly linked it to maritime defense, comparing it with U.S. sensor networks. Wu Lixin, the scientist who proposed the initiative, now oversees the network through the Qingdao National Laboratory for Marine Science and Technology, which partners with China’s Naval Submarine Academy.
Naval-warfare specialists warn that the data is strategically invaluable. Peter Scott, former chief of Australia’s submarine force, told Reuters that the surveys “would be potentially invaluable in preparation of the battlespace” for Chinese submarines. Tom Shugart, a former U.S. submarine commander, explained that sound propagation—critical for sonar detection—is influenced by seabed terrain, water temperature, salinity, and currents, all of which China is now mapping with unprecedented precision. Rear Admiral Mike Brookes, director of the U.S. Office of Naval Intelligence, testified to Congress that China’s expanded surveying “enables submarine navigation, concealment, and positioning of seabed sensors or weapons” and represents a serious strategic concern.
Experts emphasize the potential consequences for U.S. and allied naval operations. Ryan Martinson, an associate professor at the U.S. Naval War College, said, “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.” Collin Koh, a maritime security analyst in Singapore, added that China now possesses a comprehensive understanding of the waters in which it hopes to operate, both in peacetime and during conflict.
The scale and scope of China’s oceanic research are unprecedented. Hundreds of sensors, buoys, and subsea arrays have been deployed around critical maritime routes, from the South China Sea to strategic areas off Hawaii and the Indian Ocean. Chinese publications describe the goal of transforming scientific data into “new types of combat capabilities” for its naval forces, demonstrating how civilian research underpins military modernization. Zhou Chun, overseeing sensor arrays in the Pacific and Indian oceans, has emphasized the rapid development of China’s maritime defense and the potential to leverage scientific achievements into operational advantage.
China’s mapping and monitoring effort signals a shift in undersea strategy that could reshape the balance of naval power in the Indo-Pacific and beyond. By creating a detailed “map” of the seabed, currents, and oceanic conditions, Beijing is preparing its submarine forces for potential confrontation with the United States, its regional allies, and other naval powers. For observers, the campaign is a clear indicator of China’s ambition to project power across the world’s oceans and secure its maritime interests in an era of intensifying strategic competition.
