 "Sava" was laid down on 3 January 1942 as "Nautilo", the eighth boat of the Type 1 "Flutto"-class submarines that were being built for the "Regia Marina" (Royal Navy) by Cantieri Riuniti dell'Adriatico, Monfalcone.The boat was launched on 20 March 1943 and completed by 26 July the same year.As completed, the boat measured in length overall, with a beam and a draught of .