The UK Royal Navy's third Astute-class submarine HMS Artful is set to start sea trials after final construction was completed at BAE Systems shipyard in Barrow-in-Furness in Cumbria.
HMS Artful is expected to join the Royal Navy fleet around the end of this year.
UK Defence Secretary Michael Fallon said: "The Astute submarine programme is a key part of our £163bn plan to ensure that our armed forces have the equipment they need.
"Artful will now join Ambush and Astute, helping to keep Britain safe. The next four boats are already under construction, securing thousands of jobs and showing our commitment to increase defence spending each year for the rest of the decade."
The vessel completed its maiden dive at the BAE Systems dock in October last year.
The 97m-long, 7,400t nuclear-powered Artful is capable of precisely striking targets approximately 1,200 miles from the coast.
The Sonar 2076 system equipped aboard the vessel boasts a processing power of 2,000 laptops, making it one of the most powerful vessels in operation.
The Astute-class is the first class of Royal Navy submarine that are not fitted with optical periscopes. However, it features high-specification video technology, which will provide images into the submarine control room through fibre-optic cables.
The first two Astute-class submarines, HMS Astute and HMS Ambush, are currently operational with the navy, while the remaining four vessels, Audacious, Anson, Agamemnon, and the yet-to-be-named seventh boat, are in various phases of construction.
Image: The Royal Navy's latest Astute-class submarine, HMS Artful. Photo: courtesy of UK Ministry of Defence / Crown copyright.