TAIPEI (Taiwan News) — China is charting out the seabed across the Pacific, Indian, and Arctic oceans to form a detailed map useful for conducting submarine warfare against the US and its allies, according to naval experts.
The Dong Fang Hong 3, a research vessel operated by Ocean University of China, traversed waters near Taiwan and Guam, and in the Indian Ocean in 2024 and 2025, per Reuters. This mission was a part of a large-scale ocean mapping and monitoring operation deploying numerous research vessels and hundreds of sensors.
Reuters said it tracked at least eight ships carrying out seabed mapping, while 10 carried mapping equipment. The vessels travel back and forth in close lines. The data they gather is vital to submarine operations, anti-submarine warfare, and submarine detection, according to naval experts.
The mapping data “would be potentially invaluable in preparation of the battlespace” for Chinese submarines, said Peter Scott, a former chief of Australia’s submarine force. “Any military submariner worth his salt will put a great deal of effort into understanding the environment he’s operating in.”
Part of China’s seabed mapping is taking place in strategic waters around the Philippines, Guam, Hawaii, and Wake Atoll. However, the majority of operations have been east of the Philippines, which is part of the First Island Chain. The island chain stretches from Japan to Taiwan and down south toward Borneo, acting as a natural barrier between China’s coast and the Pacific.
“They’re paranoid about being boxed in to the First Island Chain,” said Peter Leavy, president of the Australian Naval Institute and former Australian naval attache to the US. China’s mapping “indicates a desire to understand the maritime domain so they can break out.”
Jennifer Parker, an adjunct professor of defense and security at the University of Western Australia and former Australian anti-submarine warfare officer, said, “The scale of what they’re doing is about more than just resources.” She added that “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.”
“It is frankly astonishing to see the enormous scale of Chinese marine scientific research,” Ryan Martinson, an expert on Chinese maritime strategy at the US Naval War College, said. “For decades, the US Navy could assume an asymmetric advantage in its knowledge of the ocean battlespace,” Martinson added. China’s operations “threaten to erode that advantage. It is obviously deeply concerning.”
