Nistar-class

The Nistar class consists of two diving support vessels built by Hindustan Shipyard for the Indian Navy. The Indian Navy signed the contract with Hindustan Shipyard to design and construct the vessels on 20 September 2018 for ₹2,392.94 crore. Steel Authority of India Limited supplied the steel used for construction. Keel laying for the lead ship, INS Nistar, took place on 28 December 2019, followed by Nipun on 23 March 2020. Both vessels were launched on 22 September 2022. Hindustan Shipyard delivered INS Nistar on 8 July 2025, and the ship was commissioned into the Eastern Naval Command at Visakhapatnam on 18 July 2025. Nipun was delivered on 30 July 2026. The vessels replaced commercially leased ships such as SCI Sabarmati, which had performed diving support duties following the 1989 decommissioning of an earlier Soviet-built submarine rescue ship named INS Nistar.

Designed by Hindustan Shipyard in consultation with Vik-Sandvik in accordance with Indian Register of Shipping rules, the Nistar class features 80 percent indigenous content. The vessels serve as mother ships for a Deep Submergence Rescue Vehicle and two Observation-class Remotely Operated Vehicles. Onboard diving and rescue equipment includes a DP-II Dynamic Positioning System, an air and mix gas diving system, a six-person decompression chamber, a moon pool-launched Submersible Decompression Chamber, a Self-Propelled Hyperbaric Lifeboat, side-scan sonar, and a 15-tonne subsea crane. Sensor and combat systems include a navigation radar, two BEL Lynx-U2 fire-control systems, an electro-optical infrared search and track fire-control system, an electronic warfare suite, and two 30 mm AK-630 close-in weapon systems. Aviation facilities feature a helipad sized for a 15-tonne helicopter.

INS Nistar completed maiden sea trials on 27 May 2024 and air and mix gas diving trials in April 2025. On 14 September 2025, Nistar arrived at Changi Naval Base in Singapore to participate in Exercise Pacific Reach 2025 in the South China Sea. During the exercise, Nistar deployed the Submarine Rescue Unit (East) and the Deep Submergence Rescue Vehicle Tiger X to perform consecutive mating operations with the Republic of Korea Navy submarine ROKS Shin Dol-seok and the Republic of Singapore Navy submarine RSS Invincible. Nistar led the formation during a three-asset rescue drill alongside the Republic of Singapore Navy ship MV Swift Rescue and the Japan Maritime Self-Defense Force ship JS Chiyoda. In February 2026, Nistar demonstrated its rescue capabilities to foreign naval delegates at Visakhapatnam during the International Fleet Review 2026.