Chinese submersible drones’ sinister roles in expansionism

First, there were the “Ocean E-Stations,” and then came the sea drones retrieved from the waters off Luzon, Visayas, and Mindanao in 2022 and 2024.

In 2018 and 2020, the Asia Maritime Transparency Initiative (AMTI) reported that China has deployed a network of sensors and communications capabilities between Hainand Island and the Paracels.

These, it said, “are part of a ‘Blue Ocean Information Network’” developed by a state-owned company to “aid in the exploration and control of the maritime environment using information technology.”

As the AMTI said, while the network is cast as an environmental monitoring and communications system, “the military utility of its sensing and communications functions” makes its development important to monitor.

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China, in 1987, seized Fiery Cross, or Kagitingan Reef “on the pretext of building a weather radar station to assist Unesco in its global oceanic survey.”

But a few decades later, the reef has been “dredged and reclaimed [...] into a 270-hectare island” that has a “military airbase with a three kilometer military grade runway and a seaport.”

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AMTI explained that the most visible elements of the network are two types of “Ocean E-Stations” called “floating integrated information platforms” and “island reef-based integrated information systems.”

It said both the floating and fixed platforms are intended to host different sensors and act as a communications conduit for the information that they collect, like data on current, temperature and salinity.

But while there was no specific mention of underwater monitoring systems like sonar or hydrophones that could be supported by the floating platforms, other kinds of observation devices can be installed.

This, as the China Electronics Technology Group Corporation described the integrated information platforms as being part of a “Blue Ocean Information Network,” which may include other components such as these:

• Ocean buoys


• Fixed and relocatable underwater sensors like sonar and hydrophones


• Unmanned aerial vehicles


• Unmanned submersible vehicles


• Unmanned surface vehicles

As AMTI pointed out in its report “Exploring China’s Unmanned Ocean Network,” these and the rest of the system “raise several concerns in the South China Sea and beyond.”

PH retrieves submersible drones

Fast forward to 2022, the Philippine Navy (PN) said two underwater drones were recovered in the waters off Pasuquin, Ilocos Norte in July and off the coast of Zambales in September.

Then in 2024, four more were retrieved – two in Calayan Island, Cagayan in August, one in Initao, Misamis Oriental in October, and one in San Pascual, Masbate in December.

Rear Admiral Roy Vincent Trinidad, spokesperson for the West Philippine Sea, said there is a “50 percent to 80 percent” likelihood that most of the underwater drones were deployed by the Chinese government.

READ: Tests show underwater drones found in PH likely from China

This statement was shared by Jonathan Malaya, spokesperson of the National Security Council, who stated that “the forensic examination [...] allowed us to conclusively determine that they are of Chinese origin.”

As Trinidad pointed out, the drones, retrieved in the last two years, are small, only about “2.5 meters to 3.5 meters in length,” making them “difficult to detect” when submerged.

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But while the submersible drones are believed to have been deployed by China to map the Philippines underwater terrain, Trinidad said that some obtained key data that could be employed militarily.

“The data received focuses more on bathymetric data, depth of water, salinity, temperature, propagation of sound,” he said, stressing that all of these have applications across different areas.

He said the underwater drones also appeared to have the capability to receive, store, process, and transfer such data through satellite communication to a station on land, a “mother ship,” or other drones.

‘Sea wing’

Initially, PN said the last one, retrieved in the waters off Masbate, had the marking HY-119, and as stated in the website Covert Shores by submarine expert H I Sutton, the drone is called “Sea Wing.”

HY-119 have naval and military application, as well as civilian relevance, as they can be employed for scientific research, dynamic process observation, acoustic detection, and comprehensive exploration of the deep sea.

The glider can carry conductivity, temperature and depth sensors, as well as turbulence meter, turbidimeter, chlorophyll sensor, dissolved oxygen sensor, nitrate and other biochemical sensors.

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It can also carry acoustic sensors such as “Acoustic Doppler Current Profile,” underwater acoustic communication and hydrophones, said Sutton, who is also an underwater warfare analyst.

As Trinidad said, “any potential adversary who would like to harm our country would need to know the information, not only on land, on air, but more importantly, since we are an archipelago, underwater information”

“It is very clear that these are used for mapping out the underwater terrain, collecting information, like bathymetric data,” he said. “All of these are used across different fields to include underwater warfare.”

RELATED STORY: Zubiri says China may be mapping PH underwater terrain using drone

The areas where the submersible drones were retrieved “are important strategically in the defense and security not only of the country but for international maritime navigation,” Trinidad said.

Last year, Chinese media revealed that researchers have developed submersibles that imitate the “devil fish,” which increases efficiency, resulting in a more effective completion of complex naval missions.

‘Act of espionage’

As Sen. Francis Tolentino said, the retrieval of the submersible drones, as well as the string of alleged “spying” activities, point to a “determined, continuous, and pervasive assault” on Filipinos.

“To be clear, we are facing an unprecedented kind of spying by China,” he said.

But while a clear link between the submersibles and the “Ocean E-Stations” has yet to be established, Felix Chang, a senior fellow at the Foreign Policy Research Institute, stressed China’s capabilities in the South China Sea.

He stated in an analysis published in 2021 that “detecting, identifying, and tracking ships at sea are among the most important intelligence, surveillance, and reconnaissance tasks that any country must perform if it wants to exert control over a maritime area.

“So, it is hardly surprising that China, especially after the early 2010s, has significantly boosted its ISR capabilities in those waters, and none more so than in the South China Sea,” he said.

For Chang, its ISR capabilities have already helped China better assert its illegal claims over the waters within its self-proclaimed nine, now 10-dash line” in the South China Sea.

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“But Beijing has not stopped there. It continues to heavily invest in ever more precise and timelier ISR collection assets in the area, leading one to wonder whether China’s real intention is to develop an ISR network capable of targeting ships far out to sea,” he said.

Chang said the ISR collection assets that China has assembled in the South China Sea “span a wide range of technologies.”

“Each holds certain advantages and disadvantages. If properly woven together into a robust network, they offer Chinese commanders an increasingly accurate and persistent picture of maritime activity in the area,” he said. /tsb

(2025/06/24-14:12)