Italian submarine Perla was a built for the Royal Italian Navy (Regia Marina) during the 1930s. She was named after a gemstone Pearl. 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 . 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 Perla was built by CRDA at their shipyard in Monfalcone, laid on 31 August 1935, launched on 3 May 1936 and completed on 8 July 1936. After delivery, Perla was assigned to the 35th Squadron (III Submarine group) based at Messina, though she was operating out of Augusta. In the same year, Perla carried out an extensive training cruise that took her to Tobruk, Benghazi, Bardia, Leros, Rhodes, and other ports in the Dodecanese eventually returning to Augusta. In 1937 she undertook a similar training cruise in the Mediterranean visiting mostly domestic ports returning to Taranto. In 1938 she was assigned to the Red Sea base of Massawa in Eritrea with the task of testing the submarine performance in warm seas. From 29 December 1938 to 24 January 1939 Perla, together with , undertook a cruise off the coast of Somalia. In the spring of