The world’s biggest cruise liner has set off from Saint-Nazaire in western France on its first sea trial ahead of its official launch in May.
Harmony of the Seas, built by STX France at a cost of $1.1bn (£770m), is 362m (1,187 ft) long and weighs 227,000 tonnes.
Stood on its end it would be 50m (164ft) taller than the Eiffel Tower and is almost 100m (328ft) longer than the Titantic.
The giant vessel is due to sail from Southampton to Barcelona on its maiden voyage.
It will then begin a life of cruising around the Mediterranean and Caribbean for Royal Caribbean International (RCI) cruises.
Some 500 people, mostly crew, were on board for the trial, which is scheduled to last until Sunday.
For months, tourists have been allowed on board to view the innards of Harmony, which has 16 decks and is 70m (210ft) tall.
Three pilots, who have trained on a simulator in nearby Nantes for the past year, helped the captain perform the tricky manoeuvres needed to guide it out of the Saint-Nazaire estuary.
They were due to take their leave once the ship was 20km (12m) out at sea.
Some 2,000 crew will cater for the needs of Harmony’s 5,490 passengers.
They will have 40 restaurants to choose from together with a host of bars, shops, pools and a theatre.
Harmony is one metre wider than the other two monsters of the pleasure cruise world, the RCI-owned Allure of the Seas and the Oasis of the Seas, which are also 362m long.
Further trials will take place before the end of April, with delivery set for 12 May – two years and eight months after construction began.