S-80 Plus-class (Isaac Peral-class)

The class originated from late 1990s requirements intended to replace aging diesel-electric vessels. Production was formally ordered in 2003, reflecting a strategic shift from static coastal defense toward oceanic power projection. The development phase encountered significant technical challenges, most notably a major weight miscalculation discovered in 2013 that necessitated an extensive redesign. To restore buoyancy, the hull was lengthened by approximately 10 meters. Economic constraints and technical refinements further extended the development timeline, leading to the first unit's commissioning in late 2023.

These are medium-tonnage oceanic submarines engineered for stealth and long-endurance operations in remote theaters. The platform incorporates an advanced air-independent propulsion system utilizing a bioethanol processor and fuel cells, which extends submerged autonomy. The design emphasizes signature reduction, targeting acoustic, magnetic, radar, and infrared profiles to minimize detectability. An integrated combat system manages multiple target acquisition and command functions, while a high degree of automation allows for a reduced crew complement. The vessel is equipped to deploy various ordnance, including heavyweight torpedoes, anti-ship missiles, and land-attack cruise missiles, and can facilitate the transport of special operations personnel.

The primary operator is the Spanish Navy, which commissioned the lead ship of the series in November 2023. These vessels are intended for deployment in high-threat scenarios and international exercises, providing a platform for persistent presence in potential conflict zones. Current procurement plans involve a series of four units, with subsequent deliveries scheduled through 2029. While primarily serving national strategic interests, the design has also been presented as a candidate for various international naval modernization programs.