A cruise ship or a cruise liner is a passenger ship used for pleasure voyages, where the voyage itself and the ship's amenities are considered an essential part of the experience. Cruising has become a major part of the tourism industry, with millions of passengers each year as of 2006. The industry's rapid growth has seen nine or more newly built ships catering to a North American clientele added every year since 2001, as well as others servicing European clientele. Smaller markets such as the Asia-Pacific region are generally serviced by older tonnage displaced by new ships introduced into the high growth areas.
Cruise ships operate on a mostly set roundabout course (i.e. they tend to return to their orginating port) whereas ocean liners are defined by actually doing ocean-crossing voyages, which may not lead back to the same port for years.
Present-day cruise ships are organized much like floating hotels, with a complete "hospitality staff" in addition to the usual ship's crew. It is not uncommon for the most luxurious ships to have more crew and staff than passengers.
As with any vessel, adequate provisioning is crucial, especially on a cruise ship serving several thousand meals at each seating. The amount of food and beverages consumed on cruise ships is staggering. Passengers and crew on the Royal Caribbean International ship Mariner of the Seas consume 20,000 pounds (over 9,000kg's / nine tonnes) of beef, 28,000 eggs, 8,000 gallons (over 30,000 litres) of ice cream, and 18,000 slices of pizza in a week.
Many older cruise ships have had multiple owners over their lifetimes. Since each cruise line has its own livery and often a naming theme (for instance, ships of the Holland America Line have names ending in "-dam", e.g. MS Statendam, and Royal Caribbean's ships' names all end with "of the Seas"), it is usual for the transfer of ownership to entail a refitting and a name change. Some ships have had a dozen or more identities.
Cruise ships and former liners often find employment in applications other than those for which they were built. A shortage of hotel accommodations for the 2004 Summer Olympics led to a plan to moor a number of cruise ships in Athens to provide tourist accommodation. On September 1, 2005, FEMA contracted three Carnival Cruise Lines vessels to house Hurricane Katrina evacuees.