SOMEWHERE, not far off Hampshire's coastline, a vast floating city of the future makes its way slowly along the English Channel.

A fleet of high-speed craft ferry thousands of people to and from the gargantuan structure while other visitors land by aircraft on the vessel's upper deck.

More than a mile long, 25-storeys high and with 200 acres of open space, this vision of cruising to come will be home to 40,000 full-time residents with enough facilities to welcome a further 30,000 every day, together with hotel accommodation for 10,000 guests and all cared for by 20,000 crew.

This gigantic superstructure, far too large to ever enter port, will constantly circle the globe and feature schools, together with a first-class hospital in addition to retail and wholesale shops, banks, hotels, restaurants, entertainment facilities, casinos, offices, warehouses, and light manufacturing and assembly enterprises.

The ideas and look of the Freedom Ship may all sound like the stuff of science fiction fantasy but this is just one of a number of serious design concepts, already drawn up, envisaging how cruise ships might look in the decades ahead.

Other blueprints call for the construction of an enormous mothership capable of launching smaller vessels while a third design shows a sleek, streamlined ship capable of taking thousands of passengers on worldwide voyages with no impact on the environment.

Many will dismiss these designs as products of vivid imaginations but it is worth remembering that, say, just 15 years ago, no one would have taken seriously any suggestions that cruise ships would one day have 900- seater ice-rinks, parks with lawns, trees and shrubs, open-air theatres, nightclubs suspended 200ft above the waves, onboard "streets'' lined with shops, bars, cafes and pubs, rock climbing walls and cocktail lounges that move up and down between decks.

In 2008 all these passenger facilities are now a reality and have been incorporated in the latest vessels to come into service.

The design for the Freedom Ship has been drawn up in America while details of the other two futuristic vessels have been revealed as the industry predicts that two million British people will be taking cruises by 2012.

These British designs come from Fredrik Johansson, senior architect at Tillberg Design AB, who helped create many of the areas on Southampton's Queen Elizabeth 2 and Queen Mary 2, and Independence of the Seas Mr Johansson said: "These designs are ships of the future, constructed with natural timeless materials and a crisp contemporary design.

The new generation of vessels will have a distinct identity throughout - from the exterior and interior design through to the onboard activities, food concepts and shore excursions.

"They are aimed at the next generation of youthful, design-savvy and environmentally-conscious passenger who we now see entering the market."

At present a total of 44 new cruise ships, worth more than £12 billion, ranging from mega-ships through to small, intimate, ultra-luxury boutique vessels, are on order, to be delivered over the next four years.