Explained: What Are Chinese Survey Ships Up To In The Indian Ocean 

In January this year, two Chinese survey vessels were spotted in the Indian Ocean, south of the Andaman and Nicobar Islands.

The Chinese ships surveyed a large area around the Ninety East Ridge, a linear, north–south-oriented, volcanic feature on the bed of the Indian Ocean.

While one of these survey vessels appears to have entered the Indian Ocean through the Malacca Strait, the other could have reached through the Sunda Strait between the Indonesian islands of Java and Sumatra.

This isn’t the first time a Chinese survey ship has been seen close to the Andaman and Nicobar Islands. In fact, in September 2019, India had spotted a Chinese research vessel in its exclusive economic zone around the islands and expelled it. Identified as Shi Yan 1, the Chinese survey ship was spotted in Indian waters west of Port Blair, operating without permission from Indian authorities.

While there are no restrictions on conducting marine scientific research in international waters under United Nations Convention on the Law, states are required to seek permission at least six months in advance for marine scientific research in another country’s EEZ or continental shelf.

With the People’s Liberation Army Navy’s (PLAN) expanding footprint in Indian Ocean, Chinese research vessels now make regular forays to the region, making multiple trips every year to survey vast swaths of the ocean.

Take the case of Xiang Yang Hong 03, a survey vessel which joined the State Oceanic Administration’s fleet in March 2016. A frequent visitor to this region over the last few years, the vessel entered the Indian Ocean through the Sunda Strait in November 2019.

In the following months, it surveyed waters west of Indonesia and in the Bay of Bengal, close to the Andaman and Nicobar Islands. In November, it was spotted in the Western Indian Ocean, surveying a large area east of the African coast.

A study by the Asia Maritime Transparency Initiative, in which state-owned or -operated survey vessels in waters beyond their government’s legal jurisdiction were tracked between April 2019 and March 2020, found that China operated “by far the largest fleet of government research vessels” in the Indo-Pacific.

China has also been deploying its underwater drones in the Indian Ocean. Over the last two years, multiple Chinese underwater drones have been found close to the chokepoints which connect the Indian and the Pacific oceans.

In February 2019, a Chinese underwater drone was discovered in Indonesian waters near the northern tip of Bangka Island in the northern part of the country.

In March that year, another Chinese underwater drone, labelled ‘Sea Wing’ and ‘China Shenyang Institute of Automation’ in Chinese characters, was found by an Indonesian fisherman near Riau Islands.

This was followed by the discovery of another underwater drone of the PLAN lurking in Indonesian waters in December 2020 near Selayar Island.

China had deployed at least 12 Sea Wing underwater drones in the Indian Ocean in 2019 using its survey ship Xiang Yang Hong 06.

“The 12 underwater gliders carried out cooperative observation in a designated sea area. Together they travelled more than 12,000 km and conducted more than 3,400 profiling observations, obtaining a large number of hydrological data...,” the Chinese Academy of Sciences said in March 2020.

China’s torpedo-shaped underwater drones, also called Haiyi, are unpowered. Instead of using battery power, these drones use variable-buoyancy propulsion to glide in water. The drones generate forward movement by first sinking to a desirable depth and then rising. This is achieved by inflation and deflation of a balloon-like device filled with pressurised oil.

Both underwater drones and survey vessels help the PLAN collect the oceanography data critical for operations of its underwater platforms.

These platforms map the contours of the seabed, and collect data such as salinity, turbidity, chlorophyll and oxygen levels.

Such data can not only help China in detecting and tracking foreign submarine movements but also for planning routes which its own submarines can use for transiting through these areas while submerged.

In the most recent case, Chinese research vessels were spotted surveying the Ninety East Ridge, south of the Andaman and Nicobar Islands.

This area, which is close to the Indian Ocean chokepoints such as the Sunda and Lombok straits, is used by Chinese warships and undersea platforms to enter the Indian Ocean, is critical for submarine operations. It forms a long, uninterrupted stretch of relatively shallow water, where submarines are prone to detection.

Therefore, it is likely that that Chinese research ships spotted in this area in January this year were collecting data to aid PLAN’s submarine operations.

China vessels have surveyed the Ninety East Ridge and the area around it extensively over the past few years, especially since 2019, operating in a “lawnmower pattern,” which indicates that is was undertaking a bathymetric survey to map the seafloor.

Between 2019 and 2021, four Chinese vessels, including the two spotted in the area in January this year, have extensively surveyed this area, as can be seen in the map above in the form of disciplined liner patterns (maroon lines indicating path taken by the ships) covering the Ninety East Ridge and the area around it.