INS Nipun explained begins with a simple point about what the ship is not. It is not a destroyer, a frigate or a carrier, and it carries no weapons meant for a surface fight. The Indian Navy's newest commissioned warship is a Diving Support Vessel, built for one purpose: to put divers into deep water, keep them alive down there, and bring them back.

The ship was commissioned at Naval Dockyard, Mumbai, on Monday, with Chief of the Naval Staff Admiral Krishna Swaminathan presiding.

It is the second vessel of the Nistar class, designed and built by Hindustan Shipyard Limited (HSL) at Visakhapatnam, and its induction completes the two ship class.

What a Diving Support Vessel is

A Diving Support Vessel, or DSV, is a mother ship for underwater work. Everything aboard exists to sustain people and machines operating below the surface for long stretches at a time. Commercial versions of the type have worked the offshore oil and gas industry for decades, servicing pipelines and wellheads.

Naval versions carry the same core engineering and add a military task set: submarine rescue, salvage of sunken material, inspection of hulls and harbours, and recovery of anything the service needs back from the seabed. A DSV is measured not by weapons fit but by how deep it can work, how long it can hold divers under pressure, and how precisely it can sit over a target in a running sea.

INS Nipun explained, from saturation diving to salvage

The ship supports saturation, air and heliox diving. Air diving covers the shallow end of the range. Heliox, a helium and oxygen mix, replaces nitrogen to allow work at greater depths without the narcosis compressed air brings on.

Saturation diving is the demanding one. Divers live under pressure inside a chamber system aboard the ship for days at a stretch, transferring to and from the worksite in a bell that holds the same pressure, and decompressing only once at the end of the whole job rather than after every dive. That single change turns a short window of useful work into sustained operations, and it is why a purpose built platform is required rather than an adapted warship.

Why the ship has to stand still

Dynamic positioning does that work. The vessel holds its position over a dive site using thrusters under automatic control, correcting continuously against current, wind and swell, because a bell on a wire and a diver on an umbilical cannot tolerate the ship drifting off the worksite.

Nipun also carries remotely operated underwater systems for inspection and intervention, which go deeper than divers and survey a site first so human divers are committed only where genuinely needed. A dedicated diving complex sits alongside, with life support and medical facilities including hyperbaric treatment. The ship can also inspect, recover or intervene after underwater accidents, from a lost aircraft to a sunken vessel blocking a channel.

The role of a DSV in Indian Navy operations

Submarine rescue is the task that justifies the whole capability. A submarine disabled on the seabed with its crew aboard is among the hardest emergencies a navy can face, and no conventional warship can resolve it.

The response requires an ecosystem rather than a ship: a rescue vehicle able to mate with the stricken boat's escape hatch, hyperbaric chambers to receive survivors, divers and remotely operated vehicles to clear and survey the site, and a large platform stable enough to run all of it from the surface. India operates Deep Submergence Rescue Vehicle systems on both coasts, and the Nistar class gives those systems a purpose built ship to work from. Rescue windows run in days, not weeks, which is what makes the capability worth holding standing rather than assembling after an emergency starts.

There is a diplomatic dimension too. The Navy has been working towards the role of preferred submarine rescue partner in the Indian Ocean Region, a position that rests on being able to sail specialist assets to a neighbour's emergency quickly, since most regional navies operating submarines do not hold this capability themselves.

Routine work fills the rest of the calendar. Diving teams inspect hulls and harbour infrastructure, clear obstructions and train with partner navies, as the Indian Navy and US Navy did at Kochi in August on explosive ordnance disposal and wreck location. Humanitarian work with an underwater element, after a cyclone or a maritime accident, falls to the same ships.

What the Nistar class is

The class runs to two ships and no more. The contract with HSL was signed in September 2018, both hulls were launched together at Visakhapatnam in September 2022, and INS Nistar reached commissioning in July 2025 as the first indigenously designed and built DSV in Indian service. Nipun was delivered to the Navy on 30 July this year. The two ships are now split across the seaboards, Nistar under the Eastern Naval Command and Nipun under the Western Naval Command.

The crest and the name

Nipun is Sanskrit for adept, well versed in a discipline. The crest carries a whale and a diving helmet, the whale for depth and endurance and the helmet for the diver at the centre of the mission, under the motto Far Beneath, Few Beyond.

Smaller craft handle the shallow end of the same trade, and the two are complements rather than substitutes. Titagarh Rail Systems has been delivering Diving Support Craft to the Navy from Kolkata, vessels sized for coastal and harbour work rather than the deep sea, long endurance missions the Nistar class exists for.

Where the class fits in Indian shipbuilding

Building a DSV is a systems integration story more than a steel one. The diving complex, the hyperbaric plant, the dynamic positioning suite and the launch and recovery gear each sit in a specialist trade of its own.

Nipun's delivery carried indigenous content near 75 percent, with more than 120 MSME vendors engaged across the two ships through the government's GeM portal.

HSL is one of four Indian Navy shipbuilding yards under the Ministry of Defence, and the Nistar class is the first time an Indian yard has designed and built a diving support ship of this size, the kind of supplier depth the Aatmanirbhar Bharat push in shipbuilding was meant to build. Nistar's commissioning last year was the proof of concept, and Nipun completes the pair.