The world's longest ships are listed according to their overall length (LOA), which is the maximum length of the vessel measured between the extreme points in fore and aft. In addition, the ships' deadweight tonnage (DWT) and/or gross tonnage (GT) are presented as they are often used to describe the size of a vessel.The ships are listed by type. Only ship types for which there exist a ship longer than 300 metres (1,000 ft) are included. For each type, the list includes current record-holders either as individual ships, ship classes or standard designs, up to four runner-ups, and all longer ships that have been scrapped.The list does not include non-self-propelled floating structures such as the 488 m (1,601 ft) long Prelude FLNG.[1]

Cruise ships are large passenger ships used mainly for vacationing. Unlike ocean liners, which are used for transport, they typically embark on round-trip voyages to various ports-of-call, where passengers may go on tours known as "shore excursions".[1] They can carry thousands of passengers in a single trip, and are some of the largest ships in the world by gross tonnage (GT), bigger than many cargo ships. Cruise ships started to exceed ocean liners in size and capacity in the mid-1990s;[2] before then, few were more than 50,000 GT.[3] In the decades since, the size of the largest vessels has more than doubled.[4] There have been nine or more new cruise ships added every year since 2001, most of which are 100,000 GT or greater.[5] In the two decades between 1988 and 2009, the largest cruise ships grew a third longer (268 m to 360 m), almost doubled their widths (32.2 m to 60.5 m), doubled the total passengers (2,744 to 5,400), and tripled in volume (73,000 GT to 225,000 GT). As of January 2022, the largest cruise ship, Wonder of the Seas, has a gross tonnage of 236,857, is 362 metres (1,188 ft) long, 64 metres (210 ft) wide, and holds up to 6,988 passengers.[6][7]Cruise ships are organized much like floating hotels, with a complete hospitality staff in addition to the usual ship's crew.[8] Modern cruise ships, while sacrificing some qualities of seaworthiness, have added amenities to cater to nautical tourists, with recent vessels being described as "balcony-laden floating condominiums".[9] The "megaships" went from a single deck with verandas to all decks with verandas,[10] and feature ameneties such as theaters, fine-dining and chain restaurants, spas, fitness centers, casinos, sports facilities, and even amusement park attractions.[1][11]Cruise ships require electricity for powering both hotel services and for propulsion.[12] Cruise ships are designed with all the heavy machinery at the bottom of the ship and lightweight materials at the top, making them inherently stable even as ship designs are getting taller and taller,[13] and most passenger ships utilize stabilizer fins to further reduce rolling of tall ships in heavy weather.[14] While some cruise ships use traditional fixed propellers and rudders to steer, most larger ships use propellers that can swivel left and right to steer the ship, known as azimuth thrusters, which allow even the largest ship designs to have adequate maneuverability.[15]Cruise ships are operated by cruise lines, which are companies that market cruises to the public. In the 1990s, many cruise lines were bought by much larger holding companies and continue to operate as brands or subsidiaries of the holding company. For instance, Carnival Corporation & plc owns both the mass-market Carnival Cruise Line, focused on larger party ships for younger travelers, and Holland America Line, whose smaller ships cultivate an image of classic elegance.[16] The common practice in the cruise industry in ship sales and orders is to list the smaller operating company, not the larger holding corporation, as the recipient cruise line of the ship.[17][18]

As of June 2022, there are 56 passenger ships over 135,000 GT in service. The first ships over that size were the Voyager-class ships from Royal Caribbean Group's Royal Caribbean International (RCI). These ships, which debuted in 1998 at over 137,000 GT, were almost 30,000 GT larger than the next-largest cruise ships, and were some of the first ships designed to appeal to "non-cruisers", with features like a 4-deck-high, 400-foot-long (120 m) atrium down the center of the ship, an ice rink, and a climbing wall.[1] In 2005, the five Voyager-class ships were overtaken by the 149,215 GT Queen Mary 2, the first non-RCI passenger ship over 135,000 GT and the only passenger ship currently in service that classifies itself as an ocean liner. The QM2 was surpassed by RCI's 155,889-GT Freedom-class vessels in 2006, which were in turn overtaken by RCI's first of six planned Oasis-class vessels in 2009.[19] The Oasis-class ships, at over 225,000 GT, are at least 154 feet (47 m) wide, 240 feet (73 m) high, and accommodate over 5,400 passengers.[20]Since 2008, other cruise lines have been ordering 135,000+ GT ships. MSC Cruises introduced the first of four 137,936–139,072-GT Fantasia-class cruise ships in 2008,[21] followed in 2017 by both the 153,516-GT Seaside class and the 171,598–181,541-GT Meraviglia class.[22] Norwegian Cruise Line debuted the 155,873-GT Norwegian Epic in 2010, the first ship outside of the Oasis class with a double-occupancy capacity of over 4,000,[23] and introduced the 145,655-GT Breakaway class in 2013 and the 165,157–169,116-GT Breakaway-plus class in 2015.[24] Cruise lines belonging to Carnival Corporation & plc, Princess Cruises and P&O Cruises, debuted the first of seven 142,714-GT+ Royal-class ships in 2013,[25] and the corporation's Carnival Cruise Line, Costa Cruises, and AIDA Cruises debuted the first of seven planned 133,596–135,225-GT Vista-class ships in 2016.[26] AIDAnova, the first of Carnival Corporation's nine planned Excellence-class ships, debuted in 2018 at 183,858 GT, with future ships in the class planned for Costa, P&O, Carnival, and AIDA.[27] In 2016 and 2017, Genting Hong Kong's Dream Cruises introduced the 150,695-GT Genting Dream and World Dream, the first large ships from an Asian-owned cruise line.[28]