Two of the Royal Navy's anti-submarine heavyweights carried out training in the Atlantic.
Submarine HMS Astute and Type 23 frigate HMS St Albans faced tough weather conditions as they took advantage of working together on their anti-submarine warfare capabilities to do personnel transfer training.
St Albans' Merlin helicopter from 814 Naval Air Squadron - aka the Flying Tigers and normally based at Culdrose in Cornwall - flew between both vessels, winching submariners and sailors while battling wind and rain.
Lieutenant Commander Andrew Mitchell, flight commander on board the Portsmouth-based frigate, said: "The transfer was one of the most challenging - and professionally rewarding - experiences.
"We don't get to do this often and certainly not in such adverse weather conditions."
St Albans and Clyde-based Astute are two of the vessels that form the Royal Navy's anti-submarine capability. The Astute-class are primarily responsible for safe-guarding the nuclear deterrent, which this year the Royal Navy is celebrating 50 years of unbroken patrols.
The submarine class is the largest and most advanced attack submarines ever operated by the navy while St Albans is equipped with specialist sonar and torpedoes designed to counter submarines.
Commander John Cromie, commanding officer of HMS St Albans, said: "As we continue to hone our anti-submarine warfare alongside HMS Astute, the synergy that can be achieved by operating a Merlin, Type 23 and Astute-class submarine together represents the pinnacle of all-arms anti-submarine warfare.
"It clearly demonstrates the Royal Navy's ability to project a potent capability in the wider Atlantic to protect UK interests."
HMS St Albans is currently doing training in waters around Scotland.
