S-61 Delfín (Dolphin in Spanish) is a diesel-electric submarine of the Daphné-class (known in Spain as the Delfín class) that was used by the Spanish Navy between 1973 and 2003. During his 30 years of service, he participated in various national and international exercises and maneuvers, made more than 2,500 voyages, made more than 30,000 hours of immersion and served in this submarine more than a thousand sailors. At the time of her retirement, she was the longest-serving submarine in the history of the Spanish Submarine Fleet. In 2004 it was donated by the Navy to the town of Torrevieja (province of Alicante, Valencian Community) and converted into a museum ship, thus becoming the first "floating museum" of these characteristics in Spain. It is part of the Museo del Mar y de la Sal (Museum of the Sea and Salt). In the first ten years as a museum it received more than a million visitors. Construction and features It was built in the shipyards of Cartagena (Murcia). It's keel laying was carried out on August 13, 1968 and it was launched on March 25, 1972. It is a French-designed Daphné-class submarine (known as Delfín class or S-60 series in Spain) displaces 860 t on the surface, while submerged it displaced 1040 t. It has a length of 57.75 m, a beam of 6.74 m and a draft of 5.25,2 m. It was propelled by a diesel-electric system, made up of two diesel engines and two electric motors that transmitted to two propellers, with which it reached 13 knots of speed on the surface, and 15.5 knots submerged. The submarine was designed to dive to a depth of 300 m (980 ft) and its autonomy is 30 days. Regarding its armament, it has 12 torpedo tubes of caliber 550 mm; eight tubes in the bow, two in the stern and one in each fin. While the forward tubes contain full-length torpedoes (either against a ship or against a submarine), the aft tubes only contain shorter torpedoes (only against submarines, in self-defense). It has the possibility of replacing torpedoes with mines, but its great Achilles' heel is the impossibility of carrying reserve torpedoes due to the limited space available. It is designed for type missions: patrols against surface or submarine forces attack on maritime traffic recognition mined special operations History The Delfin-class submarine defense program (also called the S-60 series) was approved