Matsya 6000: All you need to know about India’s first crewed deep-sea submersible 

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India’s first crewed deep-sea submersible Matsya 6000, designed to explore the Indian Ocean, is likely to undertake its maiden mission in 2026, with trials in progress.

The underwater vehicle will carry three people to a depth of 6,000 metres as part of the government’s Samudrayaan (deep ocean) Mission.

Developed by the National Institute of Ocean Technology (NIOT), Chennai, the Matsya 6000 has been designed to explore the Central Indian Ocean to identify resources, conduct surveys and develop deep-sea technologies.

Typically, submersibles are deployed from a ship to the sea, where they explore, record and collect samples, offering a better understanding of deep oceans.

Submersibles are also used for tourism, adventure, rescue missions and to study wreckages. One such private mission went horribly wrong in June 2023 when a sea submersible carrying five people to the wreckage of the Titanic imploded, killing everyone aboard.

Built for extreme depths

According to a senior official of the earth sciences ministry, Samudrayaan is to the ocean what Gaganyaan is to the space for India. The Matsya-6000 is designed to carry three scientists in a 2.1-meter diameter personnel sphere made of Titanium alloy.

The spherical vessel maintains an internal pressure of 1 atmosphere, even while withstanding the immense external pressure of 720 bars, which is 1.2 times more than the expected pressure at 6,000 meters. For context, 6,000 metres is nearly double the depth of The Titanic ship wreck which lies at approximately 3,800 meters in the North Atlantic Ocean.

The submersible has three different combinations of weight drop mechanisms for ascending to the surface to ensure safety of the crew, minister of state (independent charge) for earth sciences Jitendra Singh told Parliament on March 19.

It has additional emergency power, control, and communication devices for contingencies. When not in the deep sea, it is designed to perpetually float unless made to dive through water filling in its ballast tanks. It also has a battery bank for power supply and thrusters for movement in all three directions — sides, up and down.

“All human safety parameters are continuously monitored during the operations and are communicated to the ship-based mission control centre through an acoustic modem, with the pilot communicating updates through an underwater acoustic telephone every 30 minutes,” the minister said.

It is designed for operations of up to 12 hours, with an emergency endurance of up to 96 hours, supported by a DNV (Det Norske Veritas)-certified human support and safety system (HSSS).

DNV is an internationally accredited registrar and classification society headquartered in Norway.

The HSSS avoids the freezing temperatures of the deep sea and maintains the oxygen level at 20 percent inside the vessel, the CO2 level at less than 1000 ppmv (part per million by volume), and controls humidity by measurement sensors to ensure human life comfort and safety.

Role of ISRO and DRDO

While Matsya 6000 has been developed by NIOT, a number of its parts have been built by other government organisations.

The Titanium alloy personnel sphere has been developed indigenously with the Indian Space Research Organisation (ISRO).

"The welding facility for the Matsya 6000 titanium alloy personnel sphere, using an electron beam source, by ISRO is a first-of-its-kind for such 80 mm thickness welding in the country,” said the official quoted above.

The bio-vest for the crew and select underwater applications such as the inertial navigation system are being developed with the Defence Research and Development Organisation (DRDO).

Environmental impact assessment relating to surveys and exploration is conducted with CSIR-NIO. NIOT has signed a memorandum of understanding with the French Research Institute for Exploitation of the Sea to facilitate knowledge exchange and participation with the French human scientific submersible for 6000 meters depth named NAUTILE.