Sweden Submarine Capabilities

Based at Karlskrona, the Royal Swedish Navy operates a submarine flotilla of five diesel-electric submarines: three Gotland-class vessels and two Södermanland-class (previously Västergötland-class) vessels. The Swedish Navy was the first to operate diesel vessels using an air-independent propulsion (AIP) system based on the Stirling engine.¹

Total Submarines in Fleet: 5

• Ballistic Missile Submarines (SSBNs): 0
• Nuclear-Powered attack submarines (SSNs): 0
• Diesel-electric attack submarines (SSKs): 5
• Air-independent propulsion (AIP) enabled: 5/5

Submarines

Sweden considers its submarines integral to its national defense. While originally assigned to the Baltic Sea region to counter the threat of Soviet invasion, Sweden’s submarines have recently expanded their area of operation. These vessels have begun to participate in multinational rapid reaction exercises acting in waters such as the North Sea, the Atlantic, the Pacific, the Bay of Biscay, and the Mediterranean. Their new tasks focus on reconnaissance, intelligence gathering, and surveillance.²

Sweden planned to develop a new submarine type, the Viking, but was forced to terminate its plans after Norway and Denmark withdrew from the development program in 2003 and 2004 respectively.³ Subsequently, Sweden’s Defense Materiel Administration (FMV) was tasked with initiating the preliminary planning for an even more modern submarine, the A26 class, to replace its Gotland-class vessels.⁴

In 2014, after acquiring Kockums from TKMS (ThyssenKrupp Marine Systems), Saab and the Swedish Defense Material Administration (FMV) came to an agreement regarding the upgrades on the Gotland-class vessels and the production of two Type A26 submarines. Under the 248 million USD deal, Kockums completed the upgrade of the HSwMS Gotland and relaunched the vessel in June 2018.⁵ In June 2019, Kockums completed the upgrade of the HSwMS Uppland and relaunched the vessel.⁶

In January 2019, Sweden announced the names of its two new A26-class submarines: HSwMS Blekinge and HSwMS Skåne. The first boat began construction in June 2022 and was originally scheduled for delivery in 2024, but has been delayed to 2027,⁷ The second boat was due for delivery in 2025, but will now be delivered in 2028.⁸ Like Sweden’s current fleet, the new A26 submarines will be equipped with Stirling AIP. The Stirling AIP was designed specifically for intelligence and stealth operations in shallow waters in addition to its open sea capabilities.⁹ The A26 vessels will also have a large bow section from which unmanned underwater vehicles (UUVs) can be launched and special forces can be transported. Additionally, this section can be used for reconnaissance, mine detection, mine laying, underwater mapping, and warfighting.¹⁰ Currently, Kockums is investigating several ways to improve communications with onshore command without giving up the submarine’s position, including the possible use of UUVs for communications purposes or new antennas on the submarine.¹¹

The Swedish navy added a third submarine to its budget due to the increasing seabed warfare seen during the Russia-Ukraine conflict.¹² The Swedish navy saw how it was unprepared during the suspected Russian attacks on the Nord Stream pipeline and is looking to rectify that issue.¹³ The new A26 submarines will be equipped with the ability to sense and interact with underwater pipes for this very reason.¹⁴

Ship Biographies

Gotland-Class

Sweden possesses three Gotland-class diesel-electric attack submarines. These submarines are 60.4 meters long with a 6.2-meter-wide beam and can travel up to 20 knots when submerged. These vessels were the first in the world to feature a Stirling engine air-independent propulsion (AIP) system. Their weapons systems are capable of firing torpedoes using four 533mm and two 400mm torpedo tubes.¹⁵

Södermanland-Class

Sweden possesses two of Södermanland-class (formerly Västergötland-class) diesel-electric attack submarines. These submarines are 60.5 meters long with a 6.1-meter-wide beam and can travel up to 20 knots when submerged. Their weapons systems are capable of firing torpedoes using six 533mm and three 400mm torpedo tubes.

Imports

Sweden does not import submarines.

Exports

Swedish shipyard Kockums began producing submarines for the Swedish Navy in 1914 but did not export vessels until the 1980s. This was largely due to Sweden’s policy of neutrality in international conflicts.¹⁶ Sweden’s change in export behaviour has been attributed to trying to retain the ability to develop new boats without facing increasingly prohibitive costs.¹⁷ In 1999, Kockums was incorporated into Germany’s Howaldtswerke-Deutsche Werft (HDW), then became part of ThyssenKrupp Marine Systems (TKMS) in January 2005. In June 2014, Saab acquired Kockums.¹⁸

Sweden’s Kockums shipyard exports three classes of submarines to Singapore, Australia, and Denmark.¹⁹ Kockums also refit deployed Japanese submarines with its Stirling AIP system.²⁰ Kockums offers three submarine classes for export:

• Gotland-class: hybrid diesel-electric/AIP patrol submarines, with an AIP system based on the Stirling engine
• Collins-class: diesel-electric, ocean-going, long-range patrol submarines, designed for the Australian Navy
• A26: diesel-electric/AIP submarines with advanced technology to enhance littoral abilities.
• Saab has begun to offer the new Blekinge submarine on the export market in three different sizes, from small boats for shorter ranges to larger boats for blue water navies.²¹