India's Steps Toward Human Deep-Sea Dives: Nautile to Matsya-6000 Wet Trials

India's 5,000-metre Nautile rehearsal pressuretests life support, comms, and retrieval-putting a safe, crewed 6,000-metre Matsya within reach, and responsibly unlocking ISAlicensed critical minerals.

- TDG NETWORK

India's deep-ocean program has accelerated in the 2020s under the Deep Ocean Mission (DOM), aiming to deploy an indigenous crewed submersible Matsya-6000 capable of 6,000 m depths. Key milestones include the recent event of India's first manned 5,000 m dives (using the French Nautile sub) in August 2025, and extensive wet trials of Matsya-6000 itself in 2024-2025. These developments parallel global history (e.g., bathyscaphe Trieste, Jiaolong, Alvin, Mir) and set the stage for India joining the handful of nations with deep-crewed submersibles.

Nautile Expedition to Matsya-6000

• 2021: Union Cabinet approves the Deep Ocean Mission (aka Samudrayaan), encompassing manned and unmanned submersibles, underwater vehicles and deep-sea mining R&D. This marked formal commitment to develop an Indian deep-diving capability.

• 2022-2024: NIOT (National Institute of Ocean Technology) completes design of Matsya-6000 (3-person titanium sphere) and builds subsystems under MoES (Ministry of Earth Sciences). Early dry dock tests validate life-support, ballast, thrusters and communications hardware. In late 2024, Matsya-6000 completed integrated dry tests simulating 500 m depths, then moved to L&T Shipbuilding (Kattupalli) for wet trials. In Jan-Feb 2025, eight shallow-water dives (five unmanned, five manned) were performed to qualify life-support, control systems and sensor payloads.

• Feb 2025: PIB press release confirms Matsya-6000 wet-test success. Crucially, the tests included manned dives to verify life-support reliability under pressure and communications/telemetry, though limited by shallow depth. This paves the way for a planned 500 m manned dive by end-2025. The 2.1 m sphere (to be upgraded to 80 mm titanium) is being engineered for 96 h emergency endurance and multi-node acoustic comms.