Sweden reactivates intelligence ship HSwMS Orion for seabed surveillance and drone testing.

The Swedish Navy has announced the reactivation of the signals intelligence vessel HMS Orion (A201) as a dedicated development and seabed surveillance platform, with operational return scheduled for 2028.

The program repurposes a decommissioned hull to test advanced naval systems, including unmanned platforms and sensor integration, enhancing Sweden’s capability to monitor and secure critical underwater infrastructure in the Baltic Sea. Confirmed on April 13, 2026, the initiative will see HMS Orion operate from Haninge under standard naval command, supporting telecommunications, sonar, and drone trials. The effort strengthens Sweden’s operational readiness and deterrence posture by accelerating the integration of seabed surveillance and unmanned systems critical to protecting strategic maritime assets.

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The Swedish Navy will return HMS Orion to service by 2028 as a development ship for testing naval systems and seabed monitoring technologies in the Baltic Sea. (Picture source: Wikimedia/Kemikungen)

On April 13, 2026, the Swedish Navy confirmed that the signals intelligence vessel HMS Orion (A201) will return to operational service in early 2028 as a development ship focused on testing future naval systems and seabed surveillance capabilities. The program combines the reuse of a 1984-built hull, decommissioned in 2023, with a structured modernization effort and a personnel model that includes both recruitment and the recall of experienced sailors. The HSwMS Orion is assigned to operate from Haninge, with periodic activity from Karlskrona, and will be crewed under naval command structures rather than a separate experimental unit.

The objective is to provide a controlled maritime test environment for integration of telecommunications systems, onboard sensor configurations, and unmanned systems. The reactivation also responds to increased operational attention on underwater infrastructure security in the Baltic Sea since 2022. The timeline indicates a four-year gap between decommissioning and re-entry, allowing for refit and system integration. This approach avoids procurement delays associated with a new-build test vessel. The HSwMS Orion, also known as HMS Orion, was built by Kockums and launched in June 1984 as a dedicated signals intelligence ship, operating with personnel from both the Swedish Navy and the National Defence Radio Establishment.

The vessel has a displacement ranging from 1,205 to 1,400 tons, a length of 61.2 meters, a beam of 11.7 meters, and a draught of 3.8 meters, dimensions that constrain payload expansion but support operations in confined maritime zones. Propulsion is provided by two Hedemora diesel engines, producing a maximum speed of 12 knots, equivalent to 22 km/h, which remains sufficient for stationary or slow-moving surveillance tasks. The crew includes about 26 personnel, typically composed of 8 officers and 18 to 20 sailors, including system technicians, signal operators, and engineering staff. The ship’s superstructure includes a large radome that houses antenna arrays used for communications intelligence and electronic intelligence collection, enabling interception of radio, radar, and other electromagnetic emissions.

The Orion, whose hull design was derived from the fisheries control vessel Argos, was assigned to the 1st Submarine Division, indicating integration with anti-submarine and maritime surveillance operations. During service, it conducted signal interception, traffic analysis, and electronic monitoring in support of national security requirements. The vessel was withdrawn from service in 2023 following the introduction of the HSwMS Artemis, which was ordered on April 17, 2017, and entered operational service between 2022 and 2023 after construction delays. Artemis has a displacement of about 2,200 tons, representing an increase of roughly 60 percent compared to Orion, allowing for expanded sensor arrays, crew accommodations, and endurance. The replacement addressed compliance with updated maritime safety standards and operational requirements that Orion could no longer meet in its original role.

Despite this, Orion was retained in reserve rather than dismantled, indicating that its hull, propulsion system, and basic onboard infrastructure remained functional. Retention avoided the cost and lead time of constructing a dedicated experimental vessel, which would require new design, procurement, and testing phases. The decision reflects a cost-benefit calculation where the conversion of an existing ship provides sufficient capability for trials and development tasks. The continued availability of Orion also allows separation between operational intelligence missions, now handled by Artemis, and experimental activities. The ship is being fitted with test installations for telecommunications, sensor integration, and onboard data processing systems, requiring modifications to power distribution, cabling, and equipment mounts.

Crew roles include system technicians responsible for maintaining both existing ship systems and newly installed experimental equipment, including fault diagnosis and system calibration. Personnel requirements specify prior naval service, recent technical experience onboard ships, and compliance with physical standards for maritime operations, including firefighting and damage control duties. Employment contracts are structured as fixed-term military positions, typically up to 8 years with possible extension to 12 years, reflecting the long-term nature of the program. The operational model integrates routine naval tasks with experimental work, eliminating the separation between ship crew and test personnel. This increases workload but allows direct feedback during testing phases. 

A primary mission area for the Orion’s future operations is seabed surveillance, focusing on monitoring underwater infrastructure such as fiber optic communication cables, energy pipelines, and fixed installations. This mission aligns with increased concern over infrastructure vulnerability following incidents in the Baltic Sea region after 2022, where damage to subsea assets highlighted exposure to sabotage and accidental interference. The ship will likely support testing of sonar systems, including both towed arrays and hull-mounted sensors, capable of detecting objects and disturbances on the seabed. It will also probably enable the deployment and recovery of autonomous underwater vehicles used for inspection, mapping, and monitoring of subsea routes.

Additional systems under evaluation might include distributed sensor networks such as fiber optic acoustic sensing, which can detect vibrations and acoustic signatures over long distances. Data collected from these systems could be processed using automated algorithms to identify anomalies in real time. The ship’s role is probably limited to validation of these systems and operational concepts, to inform future integration across Swedish vessels. The vessel might also be tasked with testing unmanned systems, including both surface and underwater drones, although specific models are not identified. Unmanned surface vehicles are expected to be used for patrol, reconnaissance, and communication relay roles, while autonomous underwater vehicles focus on seabed mapping and infrastructure inspection tasks.

Orion provides a stable maritime platform for launching, recovering, and maintaining these systems, as well as monitoring their performance under operational conditions. Onboard personnel can conduct iterative testing cycles, adjusting system parameters and configurations between deployments. The ship’s existing communications infrastructure might already support real-time data exchange between the vessel and deployed unmanned systems, enabling control and monitoring during trials. This reduces the need to allocate operational warships for experimental purposes, preserving fleet availability.

The approach allows testing of multiple systems under varying environmental conditions in the Baltic Sea without disrupting existing missions, a role comparable to dedicated experimental ships used by larger navies. At the program level, the reuse of Orion reduces acquisition costs compared to a new-build trials vessel but introduces operational constraints linked to its original design. The ship’s 61.2-meter length and displacement below 1,400 tons limit the number and size of systems that can be installed simultaneously, affecting the testing scope.

Its maximum speed of 12 knots restricts rapid redeployment between test areas, particularly in larger operational zones. Endurance is also lower than that of larger vessels such as Artemis, reducing continuous operational duration. However, the ship retains a functional signals intelligence architecture that supports integration of additional sensors and communication systems without full redesign. Its operational history in the Baltic Sea provides a known performance baseline in local conditions, reducing uncertainty during trials. The program reflects a shift toward incremental capability development within existing fleet structures, emphasizing cost control and adaptability. It also indicates increased prioritization of seabed-related missions within Swedish naval planning.

Written by Jérôme Brahy

Jérôme Brahy is a defense analyst and documentalist at Army Recognition. He specializes in naval modernization, aviation, drones, armored vehicles, and artillery, with a focus on strategic developments in the United States, China, Ukraine, Russia, Türkiye, and Belgium. His analyses go beyond the facts, providing context, identifying key actors, and explaining why defense news matters on a global scale.