Brazil Marks Major Naval Milestone with Delivery of Submarine Tonelero and Launch of Almirante Karam

Dual Milestones in Naval Modernization

Brazil's naval capabilities have been significantly bolstered with the simultaneous delivery of the third domestically built Scorpène-class submarine, the 'Tonelero' (S42), and the launch of the fourth, the 'Almirante Karam' (S43). Both events took place on November 26, 2025, at the Itaguaí Naval Complex in Rio de Janeiro, marking a pivotal moment in the country's Submarine Development Program (PROSUB).

The 'Tonelero' (S42) has officially joined the Brazilian Navy, while the 'Almirante Karam' (S43), previously known as 'Angostura', entered the water for the first time and will now commence sea trials. These achievements highlight Brazil's growing technological independence and its commitment to enhancing maritime sovereignty.

The PROSUB Program and Strategic Partnership

The Submarine Development Program (PROSUB) is Brazil's most ambitious naval modernization initiative, established in 2008 through a strategic partnership with France's Naval Group. The program's objectives include:

• Delivering a fleet of modern submarines
• Transferring critical technologies
• Building a sovereign naval industrial base
• Preparing for nuclear propulsion capability

The construction of these submarines is carried out by Itaguaí Construções Navais (ICN), a joint venture that has benefited from extensive technology transfer and training from Naval Group. Brazilian workers have received specialized training in France, enabling ICN to manage all phases of submarine production, from metal forming to system commissioning and testing.

Capabilities of the Riachuelo-Class Submarines

The 'Tonelero' and 'Almirante Karam' are part of the Riachuelo-class, which are derivatives of the French Scorpène-class but have been extensively adapted to Brazilian specifications and reclassified as the S-BR class. These diesel-electric attack submarines are larger than the original Scorpène model, measuring approximately 71.6 to 72 meters in length and displacing around 1,870 to 1,900 tons submerged.

They are equipped with six 533 mm torpedo tubes, capable of launching F21 heavyweight torpedoes and SM39 Exocet anti-ship missiles. The class is designed for anti-surface warfare, anti-submarine warfare, and special operations, optimized for stealth and extended underwater endurance across Brazil's vast maritime zone. The first two submarines of this class, the 'Riachuelo' (S40) and the 'Humaitá' (S41), were commissioned in September 2022 and January 2024, respectively.

Looking Ahead: The Nuclear Submarine Program

With the conventional submarine construction phase nearing completion, Brazil is now shifting its focus to the development of its first nuclear-powered attack submarine, the 'Álvaro Alberto' (SN-10). This ambitious project is considered the most technologically complex chapter of PROSUB and aims to grant Brazil unlimited submerged endurance and extended operational range, significantly transforming its ability to conduct persistent naval patrols. The construction of the 'Álvaro Alberto' leverages the expertise gained from building the conventional submarines, further solidifying Brazil's position among leading maritime powers.