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.