The fifth Astute-class submarine, HMS Anson, has been launched at BAE Systems' site in Barrow-in-Furness, Cumbria.
HMS Anson joins HMS Astute, HMS Ambush, HMS Artful and HMS Audacious in the fleet based at HMNB Faslane.
The 7,400-tonne submarines are the biggest and most powerful ever built for the Royal Navy.
They come with a number of firsts, such as being the first Navy submarines fitted without optical periscopes – instead using high-specification video technology.
The submarines also come fitted with world-leading sensors, Tomahawk Land Attack Cruise Missiles and Spearfish heavyweight torpedoes.
The submarines are also capable of circumnavigating the globe submerged and producing their own oxygen and drinking water.
If the cables on board an Astute submarine were laid out end-to-end, they would stretch from Barrow to Preston – about 222 miles.
And during a 10-week patrol, the 98-strong crew of an Astute class submarine will get through, on average, 18,000 sausages and 4,200 Weetabix for breakfast.
Cover image: HMS Artful, the third of the Royal Navy’s new Astute-class attack submarines (Picture: MOD).