Indian Navy’s New Underwater Sensor Network to Counter Chinese Submarine Threat in Indian Ocean

In a major strategic move, the Indian Navy is developing a vast underwater sensor network across key regions of the Indian Ocean to monitor and track Chinese submarine activity. This ambitious project, being carried out in partnership with the Defence Research and Development Organisation (DRDO) and private sector partners, is aimed at safeguarding India’s maritime interests amid rising underwater threats.

This initiative comes at a time when Chinese submarines and research vessels are increasingly active in the Indian Ocean Region (IOR), raising security concerns. In response, India is focusing on deploying underwater sensors in critical maritime zones like the Ninety East Ridge, Bay of Bengal, and the waters around the Andaman and Nicobar Islands. These areas lie close to major global shipping routes and important sea passages like the Malacca and Sunda Straits, making them strategically vital.

One area drawing particular attention is the Ninety East Ridge, a long underwater mountain range that offers ideal conditions for submarine movement. This region recently saw a month-long survey by a Chinese research vessel, triggering concerns about possible underwater mapping activities meant to aid submarine operations.

The sensor network being developed will include advanced technologies such as passive and active sonar systems, magnetic anomaly detectors (MAD), and superconducting quantum interference devices (SQUIDs). Passive sonar systems will quietly listen for the sounds submarines emit, while active sonar can actively locate and track them when needed. MAD and SQUID technologies will help detect even the smallest magnetic field changes caused by submerged metal objects like submarines, providing another layer of surveillance.

India’s plan mirrors the “Fish Hook Undersea Defence Line” set up by the United States and Japan in the Pacific Ocean, which uses seabed-based sensors to detect submarine activity. India hopes to build a similar early-warning system near the Andaman and Nicobar Islands, which would allow for rapid detection of any hostile submarines entering the Indian Ocean.

The need for such a system has become urgent. China’s navy now operates more than 60 submarines, many of them nuclear-powered. On top of that, Pakistan is acquiring eight advanced Yuan-class submarines from China, equipped with air-independent propulsion systems that allow them to remain underwater longer than conventional submarines. These developments pose a dual threat to India from both its eastern and western flanks.

India’s own submarine fleet is relatively limited, with 13 conventional diesel-electric submarines and delays in future projects like the Project 75I program, which aims to build more modern, longer-lasting submarines. Given these limitations, the new underwater sensor network is seen as an essential step to boost India's ability to detect and respond to underwater threats.

Key DRDO facilities such as the Naval Physical and Oceanographic Laboratory (NPOL) in Kochi are playing a crucial role in the development of this system. NPOL has a proven track record with sonar systems like the Abhay and HUMSA-UG, and will work alongside the DRDO’s SPACE (Submersible Platform for Acoustic Characterisation & Evaluation) and Ocean Data Centre to test and fine-tune the new technology.

There are also signs that India is considering deeper cooperation with international partners such as Japan and the United States. Talks are underway to explore the possibility of linking India’s sensor network with the US-Japan “Fish Hook” Sound Surveillance System (SOSUS), creating a more comprehensive and collaborative submarine detection capability across the Indo-Pacific.

In essence, India’s underwater sensor network is not just about watching the seas—it’s about sending a clear signal. It reflects a broader shift in India’s maritime strategy, where cutting-edge technology, regional partnerships, and strategic foresight come together to maintain security and dominance in one of the most vital and contested regions of the world.