A World Cruise is a cruise that lasts 3, 4, 5 or even 6 months that often visit unique ports and UNESCO World Heritage sites in several countries. You can purchase the entire world cruise, which may totally circle the globe or may just travel through a few continents. You can also purchase a segment or two of the full world cruise. A World Cruise usually has many amenities not found on other cruises. The per diem cost of a World Cruise many times is much lower than other cruises.