Oasis of the Seas is a cruise ship operated by Royal Caribbean International. She is the first of her class, the Oasis class, whose ships were the largest passenger ships in the world, until surpassed in 2023 by the Icon class. Her hull was laid down in November 2007 and she was completed and delivered to Royal Caribbean in October 2009. At the time of construction, Oasis of the Seas set a new capacity record of carrying over 6,000 passengers. The first of her class, she was joined by sister ships Allure of the Seas in December 2010, Harmony of the Seas in May 2016, Symphony of the Seas in April 2018, and Wonder of the Seas in March 2022, as well as Utopia of the Seas in July 2024. Oasis of the Seas conducts cruises of the Caribbean from her home port of PortMiami in Miami, Florida.

Cruise ships are large passenger ships used mainly for vacationing. Unlike ocean liners, which are used for transport, cruise ships typically embark on round-trip voyages to various ports of call, where passengers may go on tours known as "shore excursions". On "cruises to nowhere" or "nowhere voyages", some cruise ships make two- to three-night round trips without visiting any ports of call.