The largest privately owned residential yacht on earth is The World, a private floating community conceived in 1997 by Norwegian shipping magnate Knut Kloster. The ship is owned jointly by its residents, 130 families from 19 countries, who spend an average of four months on board each year, and it circumnavigates the globe continuously on an itinerary that they choose.

Since its launch in 2002, the ship has visited 800 ports in 140 countries. It has 165 bespoke apartments, including a six-bedroom penthouse suite, a 7,000-square-foot spa, four major restaurants, three cafes, six bars, two swimming pools, a full-size tennis court, a driving range, an art gallery, a night club, a 12,000-bottle wine cellar, and a theater. The average resident is 64, and 35 percent are under 50.

The original inventory of units sold out in 2006, but “there are a select number of Residences available for resale.”