The operation took place in May as part of the Finnish Navy’s final conscript exercise, Narrow Waters, which mirrors Sweden’s Swenex exercise. The coordinated drills aimed to strengthen international cooperation and real interoperability between partner nations.
In total, 2,700 sailors and soldiers from Finland, Sweden, Germany, and Estonia took part in the exercise. The Swedish submarine was escorted through the narrow Finnish archipelago by a Swedish Visby corvette and a Finnish missile boat.
Finnish Army units were ready at the dock with crane vehicles and fire suppression equipment to carry out the scheduled logistics operation. As soon as the submarine was moored, the crew began preparations to receive weaponry and fuel.
Before refuelling with diesel, the submarine had to discharge the water it had taken in to balance the consumed fuel weight. Once prepared, the submarine was resupplied with both light and heavy torpedoes, as well as diesel and liquid oxygen.
The liquid oxygen serves the quiet-running Stirling engines and is also used to dilute recycled breathing air after carbon dioxide is removed, preventing poisoning of the crew. According to Commander Paula Wallenburg, head of the First Submarine Flotilla, this marked the first time such a comprehensive resupply of a Swedish submarine — involving live torpedoes and advanced fuel — has been conducted under allied conditions or during Sweden’s previous non-aligned status.
“It requires extensive and precise planning under high operational secrecy, and this was done in close cooperation with our Finnish counterparts. Great credit goes to the personnel from security services, surveillance, logistics, workshops, and the submarine crew,” said Wallenburg.
The ability of allied forces to re-supply Swedish submarines with weapons and essentials boosts endurance and thereby operational capability, making Sweden’s submarine force more effective and combat-ready.
Source: Swedish Armed Forces.
