The Shishumar class vessels are diesel-electric submarines, currently in active service with the Indian Navy. These submarines are a lengthier and heavier Indian variant of the Type 209 submarines developed by the German yard Howaldtswerke-Deutsche Werft (HDW) under the internal designation Type 1500. The first two vessels were built by HDW at Kiel, while the remainder were built at Mazagon Dock Limited (MDL), Mumbai under a technology transfer agreement. The ships were commissioned between 1986 and 1994.