HELSINKI, Oct. 28 (AFP) – The world's biggest and most expensive cruise ship ever built, Oasis of the Seas, was to be handed over to the Royal Caribbean cruiseline on Wednesday at the Finnish shipyard where it was constructed.

At a cost of some 900 million euros ($1.3 billion), the mammoth vessel offers a world of luxury and a plethora of on-board activities for its 6,360 passengers and 2,000 crew.

STX Finland, a subsidiary of South Korean shipbuilder STX, will hand over the vessel to the US-based cruise company at a ceremony in Turku on Wednesday, and the ship will set sail on its four-night maiden voyage from the US port of Fort Lauderdale to Haiti on December 1.

Royal Caribbean has called the ship its ''most innovative and imaginative ship yet, (where) entertainment areas have become neighborhoods at sea.''

Catering to the traditional older crowd of cruise ship travellers as well as to young families, the Oasis of the Seas aims to be more of an activity centre than a traditional cruise ship that merely sails from port to port.

In an interview on the Oasis of the Seas' website, the head of Royal Caribbean, Richard Fain, said the image of cruiseship travellers as being rich pensioners who lounge about poolside was a misconception.

''The average age of our passengers is 44. I don't call that old, do you?'' he asked.

As a result, the new ship offers among other things pool surfing, rock-climbing or a whiz above the boardwalk on a zip line, providing passengers with enough activities to spend the entire cruise on board if they wish.

Real trees bring some nature on board and Broadway musicals and ice shows meet passengers' cultural needs as it sails primarily in the Caribbean.

The ship is 16 decks high, or 65 meters (213 feet) above the waterline, and measures 360 meters (1,180 feet) long and 47 meters (154 feet) wide.

She even has telescopic chimneys that can be lowered – necessary to sail under the bridges in the straits of Denmark after she leaves Finland.

The ship outdoes Royal Caribbean's Freedom of the Seas, delivered in 2006 and which has until now been the world's biggest cruiseship with room for some 4,400 passengers and 1,350 crew.

Royal Caribbean ordered the Oasis of the Seas in 2006 and its sister vessel Allure of the Seas in 2007.

Allure of the Seas is scheduled to be ready in autumn 2010.