Britain's new and only aircraft carrier -- the largest and most powerful ship ever built for the Royal Navy -- set off for its first sea trial in Scotland on Monday.
HMS Queen Elizabeth, a 919-foot, 65,000-tonne vessel, left the dock at the port of Rosyth on the Firth of Forth estuary near Edinburgh.
The ship cost $3.8 billion to build in a project employing 10,000 people and will be the country's future flagship.
It can operate with a crew of 1,000 and 40 aircraft.
The HMS Queen Elizabeth "leaves Rosyth for the first time," the Royal Navy said on Twitter.
Britain has been without any carrier strike capability since the government scrapped previous vessels in 2010 as part of austerity measures to curb a huge deficit.
The giant ship left the dock at high tide but will have to wait for low tide to be able to pass under the road and rail bridges across the Firth of Forth.
"I think there are very few capabilities, by any country, that are as symbolic as a carrier strike capability," commanding officer Captain Jerry Kyd told reporters.
"These are visible symbols of power and power projection," he said.
Sea trials in the North Sea will continue through the summer and the ship will eventually be taken to the Royal Navy base in Portsmouth at the end of the year.
But the ship is not due to go into service until 2020.
Queen Elizabeth II named the ship in 2014, smashing a bottle of whisky on its side.
The prime minister David Cameron said at the time that the ship "will be the spearhead of British sea power for the next half century".
The ship was built by a partnership comprising arms makers BAE Systems, Babcock, Thales and the Ministry of Defence.
The project was dogged by questions about the US-built F-35 jets due to be deployed on the aircraft carrier and about the need for mammoth aircraft carriers when Britain's military role in the world has diminished.
The F-35 stealth fighter, which is being built by the US in conjunction with Britain and other countries, has been heavily criticized for its high price tag and a series of delays over air safety concerns.
A sister ship to the new aircraft carrier, the HMS Prince of Wales, is also being built at the Rosyth Dockyard.