HMS Astute was named and launched by the Duchess of Cornwall in June 2007 before being welcomed into the Royal Navy in August 2010 at a commissioning ceremony at Faslane Naval Base on the Clyde.
The submarine weighs 7,800 tonnes, equivalent to nearly 1,000 double-decker buses, and is almost 100 metres (328ft) long.
Its Spearfish torpedoes and Tomahawk cruise missiles are capable of delivering pinpoint strikes from 2,000km (1,240 miles) with conventional weapons.
The submarine's nuclear reactor means it does not need refuelling and it makes its own air and water, enabling it to circumnavigate the globe without needing to surface.
Built by defence giant BAE Systems at Barrow in Furness, Cumbria, it was the first in a fleet of six which will replace the Royal Navy's Trafalgar class submarines.
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