The 220,000-tonne Oasis of the Seas, is being built by American company Royal Caribbean at the STX Europe shipyard in Turku, Finland. Left, a shipyard worker gives one of the giant bow thrusters a last-minute inspection.

The 1,187ft vessel, which can carry 6,296 passengers, is so big that its exhaust stack retracts so it can pass under bridges as it travels the world.

Representatives of the owner and the shipyard turned a wheel to let water into the enormous dry dock where the 65 per cent finished vessel is still being built.

It was estimated it would take around 15 hours to fill the dock as it needs 87m gallons of water to float the ship.

The £700m vessel is 40 per cent bigger than any other cruise ship afloat and has a Central Park-style open-air space the size of a football field with its own micro-climate.

The world-first attraction means guests will have the option of a sea or tree view.

There is also a bar that will move between three of the 16 passenger decks and a 750-seat aqua theatre.

Royal Caribbean hopes to bring Oasis of the Seas to Southampton, probably in November next year during its inaugural tour.