Spain’s Isaac Peral S-81 Submarine Sinks Retired Warship With One Torpedo in Live Exercise.

Spain’s Isaac Peral (S-81), the first submarine delivered under the country’s S-80 program, sank the decommissioned patrol vessel Infanta Elena with a single torpedo during the Atlantic exercise SINKEX-26. The engagement demonstrated successful weapon employment by Spain’s latest submarine generation while operating alongside surface ships and aircraft, adding a concrete firing result to its expanding record of fleet exercises and NATO deployments.

Spain’s S-81 Isaac Peral submarine at sea, with an inset showing the decommissioned patrol vessel Infanta Elena sinking after a single torpedo strike during exercise SINKEX-26. (Picture source: Spanish Navy)oD)

Key Tactical Insights:

- Torpedo Employment Demonstration: The sinking confirms successful weapon employment against a prepared ship target, providing a concrete result for the S-80 program without establishing effectiveness against a defended warship.
- Fleet Coordination: Participation alongside surface ships and aircraft exercised the submarine’s integration with a larger force, although the Navy did not disclose the targeting information exchanged during the engagement.
- Weapons Testing Continuity: Earlier torpedo launches were officially documented in June 2025, while contemporaneous reporting also described live-warhead employment. SINKEX-26 should therefore not be presented as Isaac Peral’s first torpedo firing.

The Spanish Navy announced the sinking on November 4, 2026, and published its English-language account on November 5. The service described SINKEX-26 as an opportunity to evaluate weapons, crew readiness and coordination between submarine, surface and aviation units. Its announcement did not specify the exact date of the torpedo engagement.

Participating forces included the frigates Cristóbal Colón and Navarra, the support vessel Carnota, the patrol vessel Relámpago, and a mine-countermeasures diving unit. Air participation comprised three AV-8B Harriers, a naval helicopter, a ScanEagle unmanned aircraft and a Spanish Air and Space Force maritime patrol aircraft. Captain Rafael Mira Calvo, commander of the 41st Escort Squadron, directed the activity from Navarra.

The exercise demonstrated the submarine’s ability to employ a torpedo within a coordinated fleet training environment. However, the Navy did not explain which sensors established the target track, whether other units supplied targeting information, or how the participating aircraft supported the engagement. Their presence establishes the exercise’s combined naval and aviation scope but does not prove a particular targeting sequence.

Before the exercise, Infanta Elena underwent decontamination, including removal of fuels, oils, and potentially polluting components. The Navy also reported hydrographic and environmental assessments of the exercise area, alongside monitoring procedures to protect marine mammals and civilian navigation.

Earlier torpedo launches establish a continuing weapons evaluation process

Isaac Peral had already fired torpedoes before SINKEX-26. In its June 18, 2025, account of SINKEX-25, conducted on June 15–16, the Spanish Navy explicitly reported S-81 torpedo launches for crew training and weapons evaluation. That official statement establishes earlier firing activity, although it does not specify whether those weapons carried explosive warheads.

Contemporaneous reporting provides additional context. On June 25, 2025, Cadena SER reported that Isaac Peral had completed its first torpedo launch with a live explosive charge. The available evidence therefore supports describing the latest sinking as a subsequent weapons-employment demonstration rather than the submarine’s first torpedo firing or first live-warhead launch.

The Spanish Navy lists SeaHake Mod. 4 torpedoes among Isaac Peral’s weapons. However, the SINKEX-26 announcement does not identify the model used, launch range, engagement depth or guidance sequence. The submarine’s published armament provides technical context but does not independently establish the configuration employed against Infanta Elena.

The operational distinction is significant. A successful sinking demonstrates that the submarine and its crew completed a weapon engagement against a prepared target under exercise conditions. It does not establish how the same engagement would unfold against a maneuvering combatant using countermeasures, defensive systems and damage control.

S-80 fleet status, Spanish deployments and basic specifications

The S-80 program comprises four conventional submarines designed and built by Navantia at Cartagena. Isaac Peral, delivered to the Spanish Navy on November 30, 2023, is the lead boat and the first delivered representative of this submarine generation. Its introduction into service has been followed by crew training, weapons evaluations, fleet integration and operational deployments.

Navantia’s September 23, 2026, program update placed the second submarine, Narciso Monturiol (S-82), in harbor and sea trials, while Cosme García (S-83) and Mateo García de los Reyes (S-84) remained under construction. Spain’s Defense Ministry had identified the end of 2026 as the delivery objective for S-82. A government schedule published in March 2025 listed delivery of S-83 in 2028 and S-84 in 2030; those dates represent planned milestones rather than completed handovers.

Isaac Peral’s operational employment already extends beyond domestic training. Spain’s Defense Staff reported on March 13, 2026, that the submarine had completed a month-long Mediterranean deployment under NATO’s Noble Shield operation. During that mission, it recorded more than 446 hours submerged and traveled over 2,043 nautical miles, conducting tasks associated with maritime surveillance and collective defense.

On October 16, Spanish authorities announced the submarine’s first integration into the Dédalo 26-02 expeditionary combat group, with subsequent participation planned in NATO’s Sea Guardian maritime security operation. This places the SINKEX result within a broader progression toward sustained employment alongside Spanish and allied forces, although the October announcement does not itself confirm completion of the subsequent Sea Guardian mission.

Isaac Peral measures approximately 80.8 meters long and displaces about 3,000 tonnes submerged. Navantia describes the S-80 design as capable of submerged speeds above 19 knots and operating depths greater than 300 meters. The manufacturer lists a core crew of 32, with eight additional personnel spaces, although actual embarked complements can vary with mission and training requirements. The Navy identifies six torpedo launchers and SeaHake Mod. 4 torpedoes for engagements against surface ships and submarines.

Propulsion remains a key difference between the boats’ current and planned configurations. Isaac Peral operates without the class’s intended BEST air-independent propulsion system. The Navy identifies S-83 and S-84 as the first submarines scheduled to receive AIP during construction, with S-81 and S-82 intended to receive it during their first major overhaul.

BEST uses hydrogen produced from bioethanol, together with oxygen, to generate electricity through a fuel cell while submerged. This reduces the need to snorkel to charge diesel-powered batteries. Navantia advertises submerged endurance of up to three weeks for the AIP-equipped design, a capability that should not be attributed to Isaac Peral’s present configuration.

For Spain and its NATO partners, SINKEX-26 adds a tangible weapons result to the lead S-80 boat’s operational record. The demonstrated achievement is specific: Isaac Peral successfully employed one torpedo to sink a decommissioned patrol vessel during a coordinated fleet exercise. Engagement performance against an actively defended adversary remains beyond what this event establishes.

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Written by Alain Servaes – Chief Editor, Army Recognition Group
Alain Servaes is a former infantry non-commissioned officer and the founder of Army Recognition. With over 20 years in defense journalism, he provides expert analysis on military equipment, NATO operations, and the global defense industry.