Post commissioning of Vela class submarines in 1973, it became necessary to build the basic infrastructure for operating and maintaining submarines in Mumbai. The first accommodation for submarine crew was a seven stored building that housed the office of the Captain Submarine (SM) of the 9th Submarine Squadron. The Captain SM of the squadron for some time was also the Commanding Officer of the submarine depot ship, INS Amba. The appointment was subsequently bifurcated, and a full-fledged Submarine Base began functioning in Mumbai. As new submarines joined the West Coast, need for additional space for setting up technical, administrative and logistics support facilities for these submarines was felt. Accordingly, work on the A-14 building, near South Breakwater began. The foundation stone was laid by Vice Admiral KK Nayyar on 06 Sep 1985. The A-14 building was inaugurated as Submarine Base Complex (SMBC) on 22 Aug 1987 by Adm RH Tahiliani, PVSM, AVSM, ADC, Chief of the Naval Staff. This four storey building contained the office of the Commodore Submarines (West), all the submarine offices and the Base Workshop.
The 12th Submarine Squadron was formed in Mar 1990 and comprised the Kilo class submarines. The 10th Submarine Squadron was formed in Feb 1992 comprising four Shishumar class submarines. Vajrabahu was the mother base for submarines of 10th and 12th Submarine Squadrons. On 01 Feb 1996, the Submarine Base Complex was commissioned as INS Vajrabahu, by Admiral VS Shekhawat, PVSM, AVSM, VrC, ADC, the then Chief of the Naval Staff. In the ensuing years, a Submarine Motion Control Simulator, Attack Simulator and a water tower building (containing storehouses for each submarine) were added. To keep up with the Mid Life Update of Shishumar class submarines, the Attack Simulator was upgraded to a reference system which replicates the complete dry end of the sonar cum Fire control system installed onboard to carry out realistic training for the submarine crew.
Today, INS Vajrabahu operates and maintains a sizeable part of the Submarine Arm, backed by a sophisticated infrastructure and well-trained, superbly motivated submarine personnel who spare no effort to keep the submarines honed and ready for action. The 10th and 12th Submarine Squadrons plan operations and provide material and logistic support to the Sindhughosh and Shishumar Class submarines based in Mumbai. The base also has a non-dieted sick bay and handles preparation and maintenance of individual escape suits for submarine personnel.