World's largest cruise ship Harmony of the Seas makes maiden voyage

The world's largest cruise ship, Harmony of the Seas, has set sail on its maiden voyage to the UK after 32 months in a French shipyard.

Costing more than $US1 billion ($A1.38 billion) to build, the 16-deck vessel is 362 metres long and holds the record for being the widest cruise ship ever built - able to carry 6360 people.

Royal Caribbean International's Harmony of the Seas has been compared to a floating city with more than 2500 staterooms, 20 dining venues, 23 swimming pools and a park with more than 10,000 plants and 50 trees.

The cruise line held a traditional delivery and flag changing ceremony in Saint Nazaire, France on 13 May 2016 following 32 months of construction.

"Harmony is truly magnificent in every sense of the word, from her architecture and design to the level of care and attention to detail with which our incredible crew are taking to prepare for our first guests," said Michael Bayley, President and CEO of Royal Caribbean International said during the ceremony.

"The ship is the 'best of the best' of what our guests love most about Royal Caribbean, combined with new and thrilling experiences never before found in one place. But it is the passion and dedication of our crew that will make everlasting memories for our guests."

Harmony of the Seas is the 25th ship in the Royal Caribbean fleet.