Italian submarine Ambra was a built for the Royal Italian Navy (Regia Marina) during the 1930s. She was named after the gemstone amber. Design and description The Perla-class submarines were essentially repeats of the preceding . The modifications that were made compared to the boats of the previous series were mostly of upgrade nature. Among them were enlargement of the false tower at the top, more modern engines, installation of a radiogoniometer that could be controlled from inside the ship. Improvements and the installation of new air conditioning equipment meant a slight increase in displacement, and increase in the fuel stowage also increased the autonomy of these boats compared to the previous series. Their designed full load displacement was surfaced and submerged, but varied somewhat depending on the boat and the builder. The submarines were long, had a beam of and a draft of to . For surface running, the boats were powered by two diesel engines, each driving one propeller shaft with overall power of . When submerged each propeller was driven by a electric motor. They could reach on the surface and underwater. On the surface, the Perla class had a range of at , submerged, they had a range of at . The boats were armed with six internal torpedo tubes, four in the bow and two in the stern. One reload torpedo was carried for each tube, for a total of twelve. They were also armed with one deck gun for combat on the surface. The light anti-aircraft armament consisted of one or two pairs of machine guns. Construction and career Ambra was built by OTO at their shipyard in Muggiano, laid on 28 August 1935, launched on 28 May 1936 and completed on 4 August 1936. Prewar (1936-1940) After delivery, Ambra was assigned to the 34th Squadron (III Submarine group) based at Messina. She was commanded by captain Cesare Corrado. After a brief training, in 1937 she carried out a long endurance cruise in the Dodecanese, and the Mediterranean visiting the North African ports in Libya. During the Spanish Civil War she was sent on a secret mission to patrol off Alicante on August 29, 1937. During the mission she attempted to attack a ship, but aborted it, failing to identify nationality of the target. She returned to base on September 6, 1937, finishing her mission. During 1938–1940 Ambra conducted several long training patrols in