INS Nistar was a submarine rescue vessel of the Indian Navy.
It was bought from reserve stock of the USSR in 1969 and was commissioned by the Indian Navy in 1971.
The ship having a displacement of 800 tonnes had the capability of rescuing the crew of a disabled submarine from deep depths, using a "rescue bell", by the dry escape method, which avoided problems associated with decompression.
Nistar was used during Indo-Pakistani War of 1971 to locate Pakistan Navy submarine PNS Ghazi, which sank off the port of Vizag.
Some of her equipment such as diving bell were later bequeathed to diving tender INS Nireekshak.