The Indian navy’s silent but deadly sub surface fighting arm has undergone tremendous changes since the first Foxtrot submarine was inducted into the service on 8 December 1967. The submarines have been a complex mix of diesel-electric – nuclear propulsion; Soviet – Western – Indian design; and imported – licence – indigenous build. Be it a two man swimmer delivery vehicle or deep water Kilo’s and HDW’s or blue water Charlie I and Akula II class SSGN’s or strategic Arihant class SSBN’s, the navy has operated the entire spectrum of submarine types. The grit and determination of the submariners is not just limited to fighting but also to build their own machines and fight. The submarine arm is also a bit of mystery and usually finds mentions in few pages in naval books or makes headlines during accidents. The book traces the origin and growth of the submarine arm of the Indian navy. The book has been written in consultation with Cmde Arun Kumar, AVSM, NM (Retd.) who has served 28 years in the submarine arm and has headed critical submarine upgrade and procurement plans. In his twenty eight years of submarine career, he held various staff and command appointments. He was Commodore Commanding Submarines (East) & Commanded INS Virbahu submarine base in the East which is regarded as ‘Alma Mater’ by the submariners of the Indian Navy; commanded the guided missile destroyer Rajput; and the Submarine Training school Satavahana. His last appointment in service was Principal Director of Submarine Acquisitions at NHQ. VAdm K.N Sushil, PVSM, AVSM, NM, ADC, Former Chief Southern Naval Command (Redt.) has written the preface. Cmde Ranjit B. Rai (Retd.) has contributed 3 chapters to the book.