A nuclear-powered submarine which ran aground on a shingle bank, embarrassing the Royal Navy, will be checked for damage today.
HMS Astute was on sea trials when the rudder of the vessel is thought to have become stuck on the bank on the west coast of Scotland at around 8am yesterday.
It is believed a crew transfer from the shore to the submarine was being carried out when the incident happened between the Isle of Skye and the mainland.
There were no reports of any injuries and the Ministry of Defence said it was not a "nuclear incident".
The vessel, described by the Navy as the UK's most powerful attack submarine, was towed free by a tug at around 6pm and sailed to deep water under its own power.
Today damage to the submarine will be assessed. It will be attached to a buoy or remain in deep water, if that is deemed more appropriate, to allow experts to carry out the survey.
The checks will determine whether HMS Astute can return to Faslane naval base on the Clyde under her own power or if the vessel requires assistance.
The Royal Navy said last night it was not known if the submarine had been damaged but experts have launched a detailed investigation, known as a service inquiry, into why the embarrassing incident occurred.
The investigation will consider if any crew were negligent and the submarine's skipper, Commander Andy Coles, could find himself in front of a court martial.
Built by defence giant BAE Systems at Barrow-in-Furness, Cumbria, HMS Astute is the first in a fleet of six vessels which will replace the Trafalgar class submarine.
A contract worth £3.5 billion was signed for the first three boats in the Astute class but there is no specific figure per submarine.
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 that it will not need refuelling in its entire 25-year life and it makes its own air and water, enabling it to circumnavigate the globe without needing to surface.
HMS Astute was named and launched by the Duchess of Cornwall in June 2007 and in August this year was welcomed into the Royal Navy during a commissioning ceremony at Faslane Naval Base on the Clyde.
As the base port of all the Navy's submarines from 2016, Faslane will be home to the whole Astute class.
The accident happened almost exactly 50 years after the UK's first nuclear submarine was launched. HMS Dreadnought was launched on October 21 1960 by the Queen.
Professor Carl Ross, a lecturer in the mechanical and design engineering department at the University of Portsmouth, worked on the structural engineering of HMS Dreadnought before its launch in 1960.
Asked whether he was surprised by yesterday's incident, he said: "They shouldn't go aground. Something has gone wrong. I'm not sure what it is, whether it is man-made or machine-made. It could be either."
When questioned about whether rudders of submarines like the Astute damaged easily, the 75-year-old said: "They do damage easily. The rudders can be caught easily in shallow waters.
"It might even damage quite a lot of it. So it could be expensive to repair."