The biggest cruise ship in the world, Liberty of the Seas, towered over Southampton docks on its recent visit - but even mightier vessels, undreamed of ten years ago, will soon be stealing the limelight. KEITH HAMILTON reports on the supersize' generation THEY just keep getting bigger, and bigger, and bigger - but Southampton ain't seen nothing yet.

A monster unlike anything before will be soon on its way to the city.

This trend of "big is best'' looks set to shape the cruise ships of the future as the industry sets a course to tempt growing numbers of passengers to the good life on the ocean wave.

But just how big is too big? That is the question some are now asking, as the capacity level of some ships pushes through the 6,000 passenger mark.

There seems to be no physical restraint to the continuing supersizing of cruise ships, as lines build larger and larger, allowing them to save with economies of scale and to add more attractions on board.

The largest cruise ship in the world, Liberty of the Seas, loomed high in the Southampton skyline recently, but it won't be long before even this enormous floating holiday resort is dwarfed by the next generation of ships - at this stage known as Project Genesis.

However, even this ambitious plan could be trumped. In Japan, moves are under way that could lead to a true sea-going colossus - the 370,000-ton Princess Kaguya which, according to the people behind the ship, will arrive in Southampton in 2012.

At first the Japanese backers wanted the 20-deck ship to be a mind-boggling 450,000 tons - equivalent to 1,125 fully loaded jumbo jets - but this has been reined in. Nevertheless, the plans still call for enough cabins to accommodate 12,400 passengers and crew.

There is no small degree of scepticism within the cruise industry about a vessel on such an unprecedented scale, but already a detailed itinerary for Princess Kaguya has been drawn up, and on August 26, 2012 she is due to make her dramatic entrance in Southampton Water.

A little earlier, sometime during the autumn of 2009 - if the cruise line Royal Caribbean International (RCI) follows its normal pattern of inaugurating new vessels - Southampton will witness an arrival that would have been impossible to imagine just ten years ago.

Miami-based RCI has built up an international reputation for bringing into service ships with unrivalled passenger facilities, such ice rinks, surfing pools and rock-climbing walls, as well as a shopping and restaurant complex centred around the Royal Promenade - an interior "street'' that runs almost the whole length of the vessel.

RCI is being rather coy about Project Genesis, but it is known that the 220,000-ton ship will have accommodation for 6,400 passengers, will be longer than three football pitches laid end to end, and with a price tag of more than $1 billion, it will be the most expensive vessel in the history of commercial shipping.

It is expected that Genesis will not only incorporate the many attractions to be found on Liberty of the Seas, but also plenty of new innovations.

Richard Fain, RCI's chairman and chief operating executive, once said: "Think of things that would be impossible to put on a ship, and Genesis will have them all.'' RCI maintains that passengers will not be put off by the size of Genesis, but rather they will experience more activities, on-board services and amenities.

In 2008, Southampton will become the home for the Independence of the Seas - sister ship of Liberty of the Seas - which is still being built in Finland.

As Independence of the Seas comes alongside the City Cruise Terminal next door to Mayflower Park, she will signal the start of a new era of ocean travel for British holidaymakers.

At a staggering 160,000 tons - the same as 400 fully loaded jumbo jets - Independence of the Seas will not be alone next spring.

Rival operator P&O Cruises is bringing into service the superliner Ventura, the latest addition to the company's Southampton-based fleet.

Ventura, being built just outside Venice, will accommodate 4,300 passengers and crew and feature a 3D cinema, a virtual Grand Prix circuit, 1,550 cabins and circus school.

By that time, Cunard's new Queen Victoria will also be operating out of Southampton, alongside Queen Elizabeth 2 and Queen Mary 2, while Norwegian Cruise Lines is bringing its vessel, Norwegian Jade to the city for a summer-long programme of voyages.

As technology grows more and more advanced, designers are able to incorporate passenger facilities that only a decade ago were just a dream.

However, these days there are ships roaming the oceans of the world fitted with West End-style theatres, water parks with hot tubs cantilevered out over the side of the vessel and ten-pin bowling alleys.

Queen Mary 2 boasts a planetarium and computerised virtual golf courses, while other ships feature 300 sq ft open-air cinema screens and even stabilised snooker tables so passengers can play in rough seas.

Southampton has the advantage over other UK ports as it has the dockside facilities to handle this new breed of 21st century cruise ships, together with a long-established experience of passenger shipping.