The Royal Navy’s new aircraft carrier is due to set sail for the first time later from the Rosyth dockyard in Fife.
HMS Queen Elizabeth – one of two new carriers being built in the yard at a cost of more than £6bn – is to begin sea trials.
She is the largest warship ever built for the Royal Navy. Her flightdeck alone is the size of three football pitches.
Once in service she can operate with a crew of 1,000 and 40 aircraft.
The 65,000 tonne warship is the Royal Navy’s first aircraft carrier since HMS Ark Royal was scrapped in 2010.
Eleven tugs will be needed to manoeuvre her out of the dock at Rosyth.
The ship will just about squeeze through the narrow entrance into the estuary.
Once there she will start her engines and wait for low tide to go under the Forth bridges.
She will have to lower a mast to make it through with just a few metres to spare.
Commanding officer Captain Jerry Kydd said the ship was important for Britain’s reputation as a naval power.
“I think there are very few capabilities, by any country, that are as symbolic as a carrier strike capability,” he added.
“Submarines you can’t see, but these are very visible symbols of power and power projection.”
The BBC’s defence correspondent Jonathan Beale said that if all went according to plan, HMS Queen Elizabeth would be sailing toward open waters on Monday evening.
He said the Royal Navy expected Russia’s military to take an interest while the warship was being tested in the North Sea.
It will be several years before HMS Queen Elizabeth is fully operational with jets on board.