At 158,000 tonnes, the Freedom of the Seas has a pool with artificial waves for surfers, an ice rink and cantilevered whirlpools that extend out from the sides of the ship, 112ft above the sea.

The new vessel, which sails next week for New York before heading down to its Miami base from where it will ply the Caribbean trade, wrested the crown as the world's biggest liner from the 151,000-tonne Queen Mary 2 launched just over two years ago.

But Freedom's time at the top may be short-lived amid talk of even larger ships. A ship codenamed Project Genesis is already set to make an appearance in 2009 at 220,000 tonnes.

The US-Norwegian owners Royal Caribbean say Freedom of the Seas, able to carry more than 3,500 passengers, was designed to appeal to the broadest consumer base possible.

But although the industry appears committed to building ever-larger ships, there is disquiet among some operators that vessels are becoming too big and the market too crowded.

Size matters

Earlier this month, the head of rival Carnival said it was shifting away from the dominant Caribbean market which has been weakened recently by hurricane fears and lower demand. Carnival said it would shift focus towards the Alaskan and European markets.

Facilities aboard the ship include
a pool with waves for surfers

"There is a downside on these big ships - the places they can go are limited," said Tony Peisley, a UK-based cruise analyst.

"The problem is, the ports are struggling to keep up with the new size of ships and the number of passengers that descend on what in some cases are relatively small towns," added Peisley, author of a report called The Future of Cruising - Boom or Bust? A Worldwide Analysis to 2015.

But Peisley said a return to smaller ships is not likely: Ports will either adapt or cruise operators will switch to new locations, he said.

"Whatever people say, the trend for bigger and bigger ships will continue for two simple reasons - the operators like them and the passengers like them."