Mediterranean cruise: what floats Marco Pierre White's boat Located in prime fleecing territory outside the walled city's main gate, Dubravka looks every inch the tourist trap. Marco prowls the terrace, glaring at other people's food. "Lots of sauces," he growls, slumping back in his chair and resuming intercourse with his telephone, a trusty shield and weapon for keeping intruders at bay. "Is your tuna fresh?" he asks the waiter. "No, from tin," the poor man replies. "Thank God!" says Marco, who is a great believer in tinning and freezing in preference to keeping things alive when past their prime. I'll have that, and then the calamari, I suppose. He does not sound optimistic. But when the squid arrives it is neither smothered in sauce nor sliced in miniature rubber rings, but a flotilla of shining torpedoes, served in all their slimy wholeness. The cloud lifts. "I think I'm going to have to eat my words about this place," says Marco. We've done well here. Nothing too adventurous - that's the trick. All present can relax and enjoy their evening. Twelve hours later we prepare for the inevitable security palaver that goes with boarding an immense cruise liner: bag and body scanning, photo ID, the works. Marco is an old hand at this and staff greet him warmly. He spends 40 days a year cruising with P & O, overseeing his restaurants: Frankie's Grill (a joint venture with Dettori) for burgers beside one of the Ventura's many pools; and The White Room on Deck 17 for fine dining on special occasions, of which there are many, a P & O cruise being a popular way to celebrate a landmark birthday or anniversary. As well as keeping an eye on business, Marco has guest appearances to make - a chat show in the theatre, a book signing and a masterclass. He rarely has time to leave the ship. That must change now that P & O has introduced food and wine cruises, with Marco and other gastro-celebs escorting excursions to fish and local produce markets, vineyards and restaurants. While the hordes tramp Dubrovnik's old walls, a small group sets off for a country restaurant near the airport. Several generations of warlike Dalmatians greet us in local costume, with local music and wine and a roasting of meat and potatoes, tagine-style, under an iron cloche and a blazing heap of hot coals. If it sounds a bit trashy, it could be, but somehow isn't (we thought). "Under the bell" cooking works a treat. "I'm going to make one of these in my garden," Marco tells the chef, who beams. He knows exactly who has come to lunch. While the meat cooks we idle in a plentiful garden filled with grapes, figs and kiwis. The group keeps its distance until the wine begins to take hold and a first brave soul plucks up the courage to approach Marco with a camera. Before he can pull out his phone, the queue has formed. They needn't have worried: Marco has time for everyone. What's your name, madam? I'm from Leeds - where are you from? You don't want a picture of me, let's have one of us together. My friend Adam will take it for you" (or better still, Marco's friend the photographer, who does the honours in good spirit). Ventura carries more than 3,000 passengers and 1,200 crew. I am new to cruising on this scale, but Marco says he loves it: cruising is his idea of the perfect holiday. You go to all these wonderful places and you don't have to move. How good is that? I am not sure, but there is no better advertisement for it than entering Venice on a sunny morning and looking down on the Doge's Palace from Deck 18, 50 metres above sea level. The entire ship's complement turns out to enjoy the scene, with one exception. Marco is hard at work below, boosting morale in the kitchen, checking the lobsters and adding his requirements to the day's shopping list, which includes 20 tons of fresh vegetables. At midday he is ready for a lunch excursion to the island of Torcello, by 007-worthy speedboat across the lagoon at high tide, squeezing under the railway bridge and swooshing past flooded churches and villa restoration projects. Never been to Torcello, Adam? You've got to do the mosaics, have your photograph taken in Attila the Hun's seat and eat at the Cipriani. And so we do, settling in to the Cipriani's exquisite garden after dispatching our sightseeing duties in 20 minutes. I choose the crab and rosemary risotto. How is it, Adam? Mmm, lovely. Marco leans across and dips in a sceptical fork. "The texture's not bad," he concedes, "but it's getting a bit sticky as it cools down. And you've got a better palate than mine if you can taste the crab. The rosemary's too much for it. Wait till you try mine. On the way back the speedboat drops us at Rialto. There is time for an expensive coffee at Florian in San Marco, with orchestra supplement, and a bellini at Harry's Bar before beating it back to the ship for Marco's turn in the theatre. He tells his story to all who will listen. A studious young chef, he formed his ideas in the classical French tradition; defined his ambition and measured his success in Michelin ratings. He has the complete set of red guides from 1900 and can recite the speciality dishes of every famous French chef since Escoffier. After achieving the ultimate - three stars and five red knives and forks - at the Hyde Park Hotel, Marco announced his retirement with a fine sense of theatre in December 1999. "The top chefs were moving out of the kitchen, and when people are paying £300 to eat in your restaurant, I think they have a right to expect you to cook," he says. The audience is more interested in Marco's television antics, and Marco is still talking when I slip away to watch Venice go by; departure at dusk is if anything more beautiful than arrival at dawn. From Deck 18 I look down on three couples who have studied the itinerary and the plan of the ship, and had the foresight to book an early table on the deck of The White Room. A glass of something fizzy to go with Marco's nonna's tiramisu, and Venice receding slowly at sunset. Good choice. Our last stop is the tiny Croatian island of Korcula, scarcely bigger than the Ventura. Not for the first time in its history, the pretty port braces itself for an invasion. Shuttle launches churn the narrow strait that separates Korcula from the steep vineyards of the Peljesac peninsula, dodging yachts and windsurfers. Passengers spew out in their hundreds and disperse to cafés, craft shops and lunch tables. "One thousand visitors at once is difficult for us," says Ivana of Filippi, a smart new waterside restaurant that takes Croatian lunch to an unexpected level of sophistication and deliciousness. On cruise day, Ivana stocks up with extra ice cream, extra coffee and extra Coke Zero. Tempted to go in, Adam? I can see that the rocks are covered with sea urchins. Marco has never seen these prickly bathing hazards in the wild before, and jumps down in his Vans to inspect them at close quarters. "At Harvey's we made sea urchin butter from their tongues and whisked it in the roasting juices," he says. Does Ivana eat urchins? "I do," our hostess replies gravely. Her husband picks them with his bare hands and they eat them raw, with a squeeze of lemon for a special occasion. Marco is charmed, as well he might be. I am beginning to feel slightly uncomfortable, as though intruding on a private moment, when a Japanese tourist thrusts a pen and paper under his nose. "You: famous cock!" declares the autograph hunter. Marco signs with a flourish and a roar of delight. The masterclass is the main event of Marco's time on board, although only a dozen passengers sign up for it. The master has given much thought to planning and "prepping." "I want them to take something away they can actually do," he says, and plans simple dishes that most people do badly, such as carbonara, and a seafood risotto which may be aimed at me. "We aren't interested in cooking," says a woman who has paid £150 to attend the 90-minute class with her husband. We just want to taste his food. You can go to famous chefs' restaurants, but they never do the cooking, do they? After boiling chopped lobster shells for stock and other laborious prepping jobs, cooking is the easy part for Marco. He may have lost some of his speed, but the man is in his element. Chop chop chop... cook cook cook, with quick-fire tips scattered like grass seed. Don't let the pasta cook the egg or your carbonara will turn to glue. And the secret of a good seafood risotto? Mascarpone, at the very last moment, instead of the traditional butter and Parmesan. Well, Adam - how does it compare with the Cipriani? No comparison, Marco. Yours tastes like... a Hockney, signed. I wish I could frame it and hang it on the wall. The Telegraph Cruise Show Open March 23-34 from 10am-5pm (4pm Sunday) at London's Olympia. Tickets £10 on the door but Daily Telegraph readers can get two free tickets at cruisingshow.co.uk or by calling 0871 620 4024 and quoting "Telegraph." A £2.50 booking fee applies. Calls cost 10p per minute plus network extras.