By Dawn Wotapka

Without ever leaving their home, Mark and Deb Bennett can spend a few nights in Copenhagen. And Italy. And even Antarctica.
Between 2011 and 2012, their residence on the high seas sailed to the seven continents, where adventures included visiting a tropical rain forest and watching walruses in the wild. If the couple feels like staying in, chefs are on standby to whip up cuisine in their home. Or they can choose among the six restaurants that are within walking distance of their one-bedroom apartment.
The Bennetts own one of the 165 private residences aboard the World, a luxury ocean liner that lets its residents spend their lives at sea. Launched in 2002, the World is the oldest and largest residential ship on the water. Now, two new competitors are on the horizon: the Utopia, a $1 billion, 200-unit residential ocean liner that developers say is about three years from being finished; and the Marquette, a planned $110 million condo boat with up to 180 residences that would travel on inland waters in the U.S.
Current and former residents of the World say that life on a luxury liner fulfills their fantasy of travel—without many of the hassles. Unit owners’ residences are for their exclusive use, so clothes and personal belongings are always on hand. Residents learn the names of their “neighbors,” and numerous social events and outings create a sense of community.
“There’s never a dull moment,” says John Demartini, a retired chiropractor and a human-behavior specialist and author who has long considered the World his home. Mr. Demartini, who formerly lived in Houston and New York City, paid around $800,000 for a one-bedroom suite.
Owners of the units, which range from studios to a penthouse with room for 12, pay annual fees of 10% to 15% of the purchase price to cover everything from staff salaries to vessel maintenance. Residents hail from 19 countries, including the U.S. and Australia, and the average age is 64, a spokeswoman says. Residences have sold for between $700,000 and $10 million, and some are currently available for resale. Mr. Bennett declined to say how much he paid for his one-bedroom residence.
Many owners keep a primary residence in their home country and use the World as a second home. Mr. Bennett, for example, is a managing partner at a law firm in Dallas, where he and his wife have downsized from a lake estate to a two-bedroom townhouse because of their travels. But even those who live on the ship full-time are subject to tax and residency requirements of their home country.
Bill Powers expects to be one of the first residents when the Utopia is ready to set sail. He plans to buy a three-bedroom unit on the vessel, where homes cost between about $4 million and $30 million. “This satisfies my wanderlust desire without the inconvenience of packing, unpacking, going through customs, avoiding the wear and tear of travel,” said Mr. Powers, 55, a general partner and senior adviser to two residential-real-estate private-equity funds. He says he looks forward to traveling with an international crowd.
“It will be an interesting, diverse group—global rather than provincial,” said Mr. Powers.
The Utopia, whose development team includes the World’s original captain and its technical team, is currently in presales, says David Robb, managing director of Frontier Group, a Los Angeles-based private-equity firm that has guaranteed the construction financing. Potential buyers can visit a 3,000-square-foot sales center set up on Rodeo Drive in tony Beverly Hills, Calif., to see a model unit. In addition to the 200 residences as large as 6,200 square feet, developers say there will be 16 smaller units for nannies and tutors. The ship is also slated to have four restaurants, a full-service spa, a casino and luxury retailers. At the onboard medical clinic, residents will be able to undergo cosmetic surgery and have stem-cell therapy for the treatment of everything from heart problems to skin disorders, Mr. Robb said. The annual maintenance fee will be about 4.5% of the list price.
Nearly 80 parties have either signed or are negotiating purchase contracts, said Chris Wheeler, the Utopia’s head of business development.
Some people remain skeptical that the Utopia, which has been in the works since 2008 and has sought little publicity, will become a reality. Mr. Robb, however, says it is definitely a go. “We’re past the point of no return,” he says. “The ship is going to get built.”
Other promising luxury residential ships have failed to materialize. The Four Seasons Ocean Residences in 2008 came close, only to see sales of units priced as high as $39 million stall after the housing and financial crisis. While deposits were taken for about one-third of the residences, financing for the $750 million project was contingent on securing two-thirds, says Erik Hvide, who was on the development team. “If we’d been 24 months earlier, it would have been no problem at all,” he says. He adds that the team would try again “if we think that the circumstances would warrant it.”
Meanwhile, developers of the Marquette, billed as the world’s largest inland passenger boat, have taken token deposits of $1,000 each for about 25% the planned units in the $110 million project, said developer David Nelson, president of River Cities Inc., which is developing the Marquette. Construction will start once it is 90% presold, at which point buyers will have to put down a more substantial deposit.
“We are a way for people to live aboard and cruise the country,” Mr. Nelson said. “The only other alternative would be buy your own house boat or yacht. We’ve made it not only a less expensive experience, but a community experience.”
The condo boat, which will include as many as 400 residents, plans to sail the nation’s northern rivers in the summer and the southern rivers in the winter. Planned features include an 18-hole chip-and-putt golf course, theaters, a grocery store and hot tubs. Prices start at $305,000 for a one-bedroom unit and go up to $1.9 million for a three-bedroom residence, Mr. Nelson said.
While some units will be sold to multiple owners who can use them a few months a year, Rick and Marcia Rotman expect to pay about $500,000 for a two-bedroom unit where they’ll live. Mr. Rotman is excited about exploring the U.S. “I just know for a few Tom Sawyer years, it’s going to be a kick and a half,” says the 65-year-old South Carolina resident, who is a retired business professor who also owned an import/export company.
Predicting the appetite for life aboard a luxury ship can be difficult. And for some, the sense of adventure wore off after several years. Robert and Janet Sabes paid $2.8 million for a 1,450-square-foot, two-bedroom, two-bath unit on the World in 2002 and sold it for about the same price in 2008. A further $300,000 went toward annual fees. Even though they spent only about half the year at sea, after 5½ years, they decided to sell.
“As much fun as it was, it’s like anything, it gets old after a while,” said Mr. Sabes, a 73-year-old Las Vegas-based restaurant developer whose latest project is a vodka ice bar in Manhattan. “There are only so many places a cruise ship can go. Once you’ve been there, you start repeating.”
“We were happy to sell,” he added. “It wasn’t like we were forced to or anything. It wasn’t our turn anymore. It was someone else’s turn.”
Mr. Bennett, the current World resident, doesn’t mind the mundane. “Some days we’re just busy with our life in the U.S. and we just hang out in our apartment, send emails, call people,” he said. “That might sound boring to some people, but we live on the ship, so we don’t have to party every day.”
For those who don’t see ownership as an option, mainstream cruise ships have been known to have the occasional long-term resident. Bea Muller, a retiree from New Jersey, famously spent several years living aboard the high-end Cunard Line’s Queen Elizabeth 2 ship before it was retired in 2008.
While there are no limits on how long someone can stay on board, says Cunard spokeswoman Jackie Chase, “the idea of one of our ships being suitable for permanent residence is simply not something we promote.”

Write to Dawn Wotapka at dawn.wotapka@dowjones.com