Susan Weissberg of Wyllys Professional Travel, in Coral Gables, Fla., arranged a "diving with sharks" surprise 50th birthday party in the Bahamas, thrown by a woman for her husband and 40 of his closest friends and relatives. For the three-night trip, Weissberg, who is PADI-certified, planned accommodations at the Lucaya Beach Hotel; all meals; use of all scuba gear; two dives each day, including one with sharks; and a souvenir, underwater video of the diving with sharks experience. The price was $45,000, not including airfare.

For more information: Wyllys Professional Travel

Robert Romano of Fugazi Travel in San Francisco planned a posh 50th birthday party in Lake Como, Italy, earlier this summer for a woman from Marin County, Calif., her husband and three other couples. Highlights included accommodations at the fabled Villa d'Este; a golf outing for men and private cooking class for women; and a private sightseeing flight via sea plane of the lake and nearby Alps. The birthday celebration at the Villa d'Este was equally memorable: It started with spa treatments for all, and ended with a black-tie dinner and special fireworks display. The price for such unforgettable pampering: $142,000, including air fare.

For more information: Fugazi Travel

Travel Artistry, Franklin Lakes, N.J.-based luxury travel consultants, created a $1 million, two-week "Mystery Trip/Great Race" for a client, his wife and 15 other couples in honor of the host's 50th birthday and 20th wedding anniversary. Celebrants met at the Beau Rivage Hotel in Geneva, Switzerland; drove rally-style in Audi TT convertible roadsters to Badrutt's Palace in St. Moritz; flew by private jet to Turkey; then raced by luxury yacht to Santorini, Greece. The final weekend of the trip was spent at the Hotel Casadelmar, overlooking the bay in Porto Vecchio, Corsica, where the group celebrated the host's milestones with 50-year-old champagne and a 20-minute private fireworks display.

For more information: Travel Artistry

New York-based Ovation Vacations recently created a 20-night, $250,000 Italian extravaganza for a couple and their two children. Top-flight accommodations included suites at the Bauer Il Palazzo in Venice, Hotel Savoy in Florence, Hotel de Russie in Rome and Hotel Santa Caterina in Amalfi. Among the unusual adventures the family experienced were dinner with a contessa in her private palace in Venice; a visit to the Lamborghini Museum and tour of the car company's factory, normally closed to the public; cooking lessons and lunch with the chef of a wine bar/restaurant outside Florence; and a private evening tour of the Vatican and its museums. Capping the end of this fabulous itinerary was a private boat trip to Capri, with a visit to grottoes sublime for swimming and sightseeing. For more information: Ovation Vacations

New York-based tour operator Heritage Tours' nine-night ultra-deluxe Morocco trip, $36,000 for two (including air fare), takes in some of the country's prime destinations, including Marrakech, Ouarzazate and Fes. Luxurious accommodations are standard throughout: A freestanding villa with a private garden at the Amanjena, a resort near Marrakech; a suite at the Dar Ahlam, a Relais and Chateaux boutique hotel in an oasis outside Ouarzazate; and the Ambassador Suite at the legendary Palais Jamai in Fes. An additional night is spent either at a homey inn right in the Sahara Desert, or camping out under the stars. Other unique experiences include visits to studios of contemporary artists in Marrkech; a tour of the city's top boutiques and artisans with a local designer; 4 X 4 excursions around Ouarzazate; and a private charter flight over the Sahara.

For more information: Heritage Tours'

A ten-night luxurious South African safari, designed for a family of five by New York-based tour operator Heritage Tours and priced at $110,000 including airfare, spares no expense while taking travelers to three of the country's most magical sightseeing spots, the city of Cape Town and game lodges Singita and Phinda Private Game Reserve. The Cape Town stay includes a dinner in the home of a family uprooted by the apartheid-era Forced Removals Act, and a catered dinner at the Groote Schuur Estate, a former residence of South Africa's prime ministers. There is even a tour of a working DeBeers diamond mine. Even transportation is stylish: Travelers use a King Air 200 as a private charter plane to visit the game lodges.

For more information: Heritage Tours'

Heritage Tours' nine-night itinerary, priced at $155,000 for a family of five, including airfare, begins and ends in Istanbul, Turkey. An enchanting middle interlude stops in the dream-like landscape of Cappadoccia, and in Bodrum, for a tour by private wooden gullet, or handcrafted sailing vessel, of the Carian city of Knidos, and a visit to the ancient city of Ephesus. In Istanbul--where accommodations are in the presidential suite of the Four Seasons at Sultanahmet at the beginning of the journey and in the Bosphorus Palace suite at the Four Seasons at the Bosphorus at the end--unique experiences include after-hours, private access to a sixth-century cistern under the streets of ancient Constantinople; a traditional Turkish dinner feast in a private yali, or mansion, along the Bosphorus; a private tour with the curator of a new museum of contemporary Turkish art; and a private, candle-lit, after-hours tour of the Kariye Museum, an 11th-century church with famed Byzantine mosaics and frescoes.

For more information: Heritage Tours'

Mansour Travel, an Ensemble travel agency with offices in Beverly Hills and Cannes, created a $475,000, month-long tour of Israel, Jordan and Egypt for 12 via private plane and helicopter. One highlight was a privately catered lunch at the Ramon Crater, the largest crater in Israel. The visit to Petra, by helicopter, included an aerial tour of this famous ancient city in Jordan, while in Cairo, the group enjoyed a private, after-hours tour of the Egyptian Museum with a personal guide and curator. Another memorable experience in Egypt: a four-day cruise on the Nile on a private vessel, complete with personal guide and chef.

For more information: Mansour Travel

Pacific Experience's 17-night Australia and New Zealand tour for two, priced at $35,000, not including airfare, lets travelers enjoy both countries' scenic splendor without sacrificing creature comforts. The first four nights are spent in a suite at Australia's Lizard Island Resort, where travelers can unwind from the rigors of their journey on any of the island's 24 Great Barrier Reef beaches. Then it's on to Ayers Rock, with two nights at Longitude 131, a luxury tented resort offering spectacular sunset and sunrise tours. The stay in Sydney features the famous Sydney Harbor Bridge climb and a surfing lesson at Bondi Beach. The trip continues with three nights in a suite at Eichardt's Private Hotel in Queenstown, offering stunning lake and mountain views, and ends on an adventurous high: a helicopter expedition to Milford Sound, called the "eighth wonder of the world" by Rudyard Kipling, and a Dart River jet-boating safari through New Zealand's southern Alps.

For more information: Pacific Experience's

Pacific Experience's 27-night trip to Japan and China for a family of five, priced at $105,000 (not including flights except those within China), features suite accommodations and activities geared to both parents and children. The stay in Tokyo, for example, includes a tour of the Suginami Animation Museum. In Hakone, there is a cruise on Lake Ashinoko, with magnificent views of Mount Fuji, while in Kyoto, travelers visit Kyoto Studio Park and Toei Movie Land, a combined film set and theme park. There's even an origami lesson in a private home here. In Beijing, travelers visit the kite market to buy kites to fly over the Great Wall, and take a tai-chi lesson and rickshaw trip through the city's hutongs, or traditional alleys. The next-to-last stop on this over-the-top vacation is Hong Kong, where travelers stay in the legendary Peninsula Hotel, take a helicopter flight over Lantau Island from the hotel's roof, and enjoy a dinner cruise at sunset on the city's magical harbor.

For more information: Pacific Experience's