Harmony of the Seas, the world's largest cruise ship, has begun its first sea trial in western France.
Thousands of people gathered to watch in the port of Saint-Nazaire as the 70m (230ft) high vessel was guided out to sea by six tugs on Thursday.
The €1bn (£783m; $1.1bn) ship is being built for the Royal Caribbean International (RCI) cruise company.
The 227,000-tonne vessel is expected to be delivered to the US-based firm in two months.
The trial will continue until Sunday.
The 16-deck Harmony of the Seas is 362m long - 50m longer than the Eiffel Tower is high.
After completion, it will be able to accommodate more than 6,000 passengers.
About 2,000 crew members will cater for their needs.