<P> The world's largest cruise ship is currently Royal Caribbean International's Harmony of the Seas beating her sister ships (Allure of the Seas and Oasis of the Seas) by about 2.15 meters . </P> <P> The birth of leisure cruising began with the formation of the Peninsular & Oriental Steam Navigation Company in 1822 . The company started out as a shipping line with routes between England and the Iberian Peninsula, adopting the name Peninsular Steam Navigation Company . It won its first contract to deliver mail in 1837 . In 1840, it began mail delivery to Alexandria, Egypt, via Gibraltar and Malta . The company was incorporated by Royal Charter the same year, becoming the Peninsular and Oriental Steam Navigation Company . </P> <P> P&O first introduced passenger cruising services in 1844, advertising sea tours to destinations such as Gibraltar, Malta and Athens, sailing from Southampton . The forerunner of modern cruise holidays, these voyages were the first of their kind, and P&O Cruises has been recognised as the world's oldest cruise line . The company later introduced round trips to destinations such as Alexandria and Constantinople . It underwent a period of rapid expansion in the latter half of the 19th century, commissioning larger and more luxurious ships to serve the steadily expanding market . Notable ships of the era include the SS Ravenna built in 1880, which became the first ship to be built with a total steel superstructure, and the SS Valetta built in 1889, which was the first ship to use electric lights . </P> <P> Some sources mention Francesco I, flying the flag of the Kingdom of the Two Sicilies (Italy), as the first cruise ship . She was built in 1831 and sailed from Naples in early June 1833, preceded by an advertising campaign . The cruise ship was boarded by nobles, authorities, and royal princes from all over Europe . In just over three months, the ship sailed to Taormina, Catania, Syracuse, Malta, Corfu, Patras, Delphi, Zante, Athens, Smyrna, Constantinople, delighting passengers with excursions and guided tours, dancing, card tables on the deck and parties on board . However, it was restricted to the aristocracy of Europe and was not a commercial endeavour . </P>

When did the first cruise ship set sail