Not that the cruise market needs a revolution-it’s already the fastest-growing segment of the travel industry. Seventeen new ships are joining the circuit this year, from the mammoth 2,766-passenger Majesty of the Seas, a floating hotel with an eye-popping atrium, to the intimate, yachtlike Renaissance VIII for 114 guests. But it’s the novel Radisson Diamond, straddling the water like a spaceship perched on its landing gear, that’s likely to make the biggest splash. In place of a traditional single hull, there are two narrow struts that extend from an elevated deck down beneath the water to two torpedo-shaped hulls; the hulls hold the engines. The space between the struts is open, so the passenger decks appear to hover above the water. What gives the Radisson Diamond its new look is a design technology called SWATH (small waterplane area twin hull). Since only a small area of the ship comes in contact with the waves, there should be less pitching, rolling and heaving in rough seas than on a conventional monohull ship of the same capacity. With the machinery underwater, far from the staterooms and public spaces, passengers will probably also notice less noise and vibration. For people afraid to take a cruise because of seasickness, this is all good news.

Twin-hull vessels have been around since the 1970s, but the 20,000-ton Finnish-built Radisson Diamond is the largest of them and the first SWATH luxury cruise ship. Diamond Cruises Inc., a joint American-Finnish-Japanese venture, and its partner, Radisson Hotels International, are targeting corporate clients: taking advantage of the Radisson Diamond’s extra breadth, they’ve installed a sophisticated conference center on board. (At 103 feet, the ship is unusually wide for its 420-foot length-the 963-foot-long superliner QE2 is only 2 feet wider.) Individual travelers can cruise the Mediterranean this summer and the Caribbean later in the year at the upscale rate of $600 a day.

Is the SWATH the wave of the future? Marine historian John Maxtone-Graham cautions “the record books are full of people who have underestimated what actually happens [with new ships] in rough weather. " But the Radisson Diamond did admirably in sea trials, and despite its cost-at $125 million about 20 percent more expensive than a comparable-size monohull-Diamond Cruises executives plan to build two more SWATHS. Obviously, they believe they have a jewel on their hands.