The Spanish Navy has taken another major step in strengthening its undersea warfare capabilities. Its S-82 Narciso Monturiol, the second submarine of the S-80 Plus class, has officially begun sea trials.

The testing program marks a crucial phase before the submarine is delivered to the fleet, with commissioning expected after all performance and safety evaluations are successfully completed.

Constructed by Spanish naval shipbuilder Navantia at its Cartagena shipyard, the S-82 is part of Spain’s ambitious S-80 Plus submarine program, which aims to replace the ageing Agosta-class submarines with a new generation of advanced, domestically designed vessels. The program represents one of the country’s largest and most technologically sophisticated defense projects, reported Naval Today.

During sea trials, the submarine will also undergo an extensive series of tests in real operating conditions. These include assessments of propulsion and power generation systems, maneuverability, diving and surfacing performance, navigation and communication systems, sonar and sensor performance, weapons integration, and overall seaworthiness.

The S-80 Plus class has been designed for a broad range of missions, including anti-submarine warfare (ASW), anti-surface warfare (ASuW), intelligence, surveillance and reconnaissance (ISR), maritime interdiction, mine-laying operations, and the deployment of special operations forces. Its advanced combat management system, modern sonar suite, and low acoustic signature are intended to enhance survivability and effectiveness in contested maritime environments.

The submarine measures approximately 265 feet (81 meters) in length, displaces around 3,000 tons when submerged, and can accommodate a crew of about 32 personnel, with additional capacity for special operations teams. It is armed with heavyweight torpedoes and anti-ship missiles launched through six 533 mm torpedo tubes, enabling it to engage both surface ships and enemy submarines.

A defining feature of the S-80 Plus program is the integration of an indigenous Air-Independent Propulsion (AIP) system, developed to significantly extend underwater endurance by allowing submarines to remain submerged for much longer without relying on battery recharging. While the first submarines are entering service before the AIP system is fully integrated, the technology is expected to be installed during future upgrades, enhancing operational flexibility and stealth.

The S-80 Plus program experienced several years of delays after engineers identified design issues, including buoyancy and weight distribution challenges that required substantial modifications. Despite these setbacks, Spain successfully commissioned the lead submarine, S-81 Isaac Peral, in 2023, demonstrating the program’s return to schedule and validating many of the new technologies incorporated into the class.

The S-82 sea trials also reflect Spain’s broader commitment to maintaining an independent submarine-building capability and supporting its domestic defense industry. The knowledge gained through the S-80 Plus program is expected to strengthen Navantia’s position in the global naval market while enhancing Spain’s contribution to NATO’s maritime security and collective defense operations.