HMS Astute sailed into the Clyde and up the Gareloch to Faslane
The Royal Navy's biggest and most powerful attack submarine has arrived at Faslane on the Clyde.
HMS Astute, which measures nearly 328ft (100m) from bow to stern, set sail from Barrow in Cumbria for its first sea trials on Tuesday.
The vessel can be armed with 38 torpedoes and missiles - more than any previous Royal Navy submarine.
It sailed into the Clyde and up the Gareloch to its new home at the Scottish naval base.
The BAE Systems-built vessel is due to go into full service next year.
It will be able to circumnavigate the entire globe underwater and advanced nuclear technology means that it will never need to be refuelled.
The submarine's arrival on the Clyde marks the beginning of a process that will see Faslane become the UK's sole operating submarine base over the next decade.
After touring the Astute, the Minister for Defence Equipment and Support, Quentin Davies, said: "This is a significant milestone for Astute as she arrives for the first time in her homeport of Faslane.
"The Astute class of submarines will deliver a step change in capability for defence in terms of anti-submarine and anti-surface warfare, protecting the deterrent, providing land attack and intelligence gathering.
"Astute will now begin a set of sea trials ahead of her full acceptance with the Royal Navy next year."
First Sea Lord, Admiral Sir Mark Stanhope, said: "The Astute Class is truly next generation.
"They are immensely powerful vessels and they will form a key part of our future programme, giving the Royal Navy the versatility and technical excellence needed to operate successfully across the globe."
Commodore Chris Hockley, the naval base commander at HM Naval Base Clyde, said: "There has been significant investment and preparations made over several years to prepare us for this occasion.
"The Clyde will become a centre of specialisation for submarines, and, of course, submarine training.
"With the arrival of Astute I cannot think of a more exciting time to be a submariner."
The Royal Navy has already spent £150m on new accommodation for submariners at Faslane.
In May a new £150m floating jetty, the length of two football pitches, was installed at the base to provide berths for the six Astute-class submarines which will eventually be based there.