Sindhughosh-Class (Type 877EM)
India possesses nine Sindhughosh-class diesel-electric attack submarines. These Kilo-class units act as the mainstay of India’s submarine fleet. They can remain submerged for about 45 days without surfacing. Their weapons systems are capable of firing torpedoes and anti-ship missiles.
Shishumar-Class (Type 209/1500)
India operates four Shishumar-class vessels designed by Howaldtswerke-Deutsche Werft (HDW) in Germany.. They can remain submerged for about 50 days without surfacing. Their weapons systems are capable of firing torpedoes. All four of the Shishumar-class vessels have undergone refits since they were commissioned. [21]
Chakra-Class
INS Chakra II is a Russian Akula-class nuclear-powered attack submarine. It is operated by Indian Navy on a lease for 10 years. It was formally commissioned into service in India in April 2012 and is expected to be returned to Russia in 2022.
Arihant-Class
India is expected to build between three to six nuclear powered ballistic missile submarines (SSBNs) under its ATV Program. They can remain submerged for about 50 days without surfacing. Their weapons systems are capable of firing torpedoes and submarine-launched ballistic missiles. However, the next ships in the class, after INS Arihant are expected to be larger and more powerful in terms of both firepower and nuclear power.
Kalvari-Class
India is expected to build six Kalvari-class diesel-electric attack submarines under its Project-75 program. The first vessel in this class was commissioned in 2017. The Kalvari class is based on the French Scorpène-class submarines. Their weapons systems are capable of firing torpedoes and anti-ship missiles.
About Project 75I:
Under Project 75I India will purchase 6 next generation diesel submarines with Air Independent Propulsion System (AIP) technology for the Indian Navy by 2022.
Conventional diesel-electric submarines have to surface every few days to get oxygen to recharge their batteries. With AIP systems, they can stay submerged for much longer periods.Project 75-I will have both vertical launched BrahMos for the sea & land targets and tube-launched torpedoes for anti-submarine warfare
