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Royal Navy’s sub hunters pit their skills against Norwegians and Germans in fjords showdown
27 June 2025
Royal Navy sub-hunters used the latest tactics against Norwegian and German submariners in a two-week battle of wits off the coast of Norway.
Two Merlin Mk2 helicopter flights – one flight each from 824 and 814 Naval Air Squadrons supported by more than 80 air and ground crew – swapped the Lizard Peninsula for the fjords of western Norway for Exercise Green Eel.
They travelled from their base at RNAS Culdrose in Cornwall across the North Sea to the spectacular cliff-top Haakonsvern Helikopter Base, overlooking a fjord near Bergen.
Their objective was to locate and aggressively track live contacts in a new and challenging underwater environment – in this case to hunt the Norwegian submarine HNoMS Utvaer and the German U-boat U34.
Joining the exercise was the frigate HNoMS Thor Heyerdahl and other ships from the Royal Norwegian Navy, as well as a support ship from the German Navy, FGS Main.
Fliers from Culdrose took part in Green Eel two years ago and Lieutenant Commander Steve Hayton, a helicopter instructor from 824 Naval Air Squadron, said the team relished the chance to return to the fjords.
“Opportunities to take part in exercises like Green Eel are invaluable and allow the instructors to hone and refresh their anti-submarine warfare skills,” he explained.
“It’s a unique exercise that allows the Merlin Mk2, which is probably the most advanced and capable anti-submarine helicopter in the world, to be pitched against the most capable submarines in the world.”
Both the Norwegian and German Navies operate traditional diesel-powered submarines – and both presented formidable ‘foes’, Lt Cdr Hayton said.
U-boats are recognised as the ‘gold standard’ when it comes to silent running while the Norwegian Ula-class submarine proved to be a similarly difficult opponent given the crew’s familiarity of operating in their own backyard.
Using sonobuoy listening devices dropped into the fjords and the Merlin’s in-built dipping sonar to locate ‘the enemy below’, the helicopter crews flew anti-submarine warfare sorties every day, amassing around 50 hours of high-quality training.
Every contour, every pinnacle, every possible place to evade detection had to be checked by the Merlins in the knowledge that the highly-skilled submariners understood their operating environment extremely well.
At the end of each day, the aviators and the submariners could then come together to debrief and learn from each other how to improve tactics above and below the water.
Captain James Hall, the commanding officer of RNAS Culdrose, said the exercise was an excellent opportunity to maintain close links with the UK’s strategic partners and NATO allies.
He said: “My thanks go to our allies, the Norwegians and the Germans, for participating in this important exercise, which has allowed us to practice our warfighting skills in a challenging, live environment.
“As well as presenting our crews with an unfamiliar area of seabed, what is particularly special about Haakonsvern is that you have all the different elements together in one place. The base accommodates the aircraft, the surface ships and the submarines.
“It means everyone involved can learn from each other to improve and evolve the exercise as it progresses, as well as understanding and countering their adversaries’ tactics. This strengthens the bond between our countries and supports our ability to work in unison within the wider NATO context.”