HMS Anson has been lowered into the water as she enters the final stages of construction.
The fifth of the Silent Service's Astute-class submarines is in the water at BAE's yard in Barrow after a delicate two-day operation.
The vessel is now being prepared for her first dive, when most of the boat is submerged in a special dry dock, ahead of leaving Cumbria next year and joining her four sister submarines in Faslane.
Anson was launched in Barrow last month.
On board the Astute-class vessel, BAE staff joined submariners, led by the boat's first commanding officer, Commander David 'Bing' Crosby, operating critical positions.
This included running the diesel engines for power, changing the ventilation states, and bringing air into the ballast tanks for buoyancy.
"The rollout itself from the dock hall is a slow and delicate operation, checking that the cradles and submarine hull are not subject to stress as the boat is rolled over the transitions onto the ship-lift," explained Cdr Crosby.
"Lowering the ship-lift also takes time, with the naval architects ensuring that all the tanks have the correct contents, so the boat maintains the correct trim as she floats.
"As she is lowered, the ship's staff are conducting rounds, leak checks and looking for floods."
He continued: "The launch marks a significant milestone in the delivery of HMS Anson to the front line.
"I am extremely encouraged by the strong relationships my team and the Royal Navy are maintaining with the BAE build team and their contracted support; these teams will ensure HMS Anson leaves Barrow in 2022 set well for sea trials ahead of what will be a long and successful operational life."
The Astute-class submarines are the biggest and most advanced attack submarines ever constructed for the Royal Navy.
They are the quietest class ever made, measure 97m long, and they also come with a number of technological firsts.
They are capable of hitting targets 1,000km from the coast and, as well as coming equipped with world-leading sensors, the submarines carry Tomahawk Land Attack Cruise Missiles and Spearfish heavyweight torpedoes.
Cover image: HMS Anson in the water (Picture: BAE Systems).