The Oasis class is a class of 7 Royal Caribbean International cruise ships. The first two ships in the class, Oasis of the Seas and Allure of the Seas, were delivered respectively in 2009 and 2010 by STX Europe Turku Shipyard, Finland. A third Oasis-class vessel, Harmony of the Seas, was delivered in 2016 built by STX France. A fourth vessel, Symphony of the Seas, was completed in March 2018. As of March 2022, the fifth Oasis-class ship, Wonder of the Seas, was the largest cruise ship in the world. A sixth ship, Utopia of the Seas, is currently being built for entry into service in July 2024 with a seventh to follow in 2028.

Harmony of the Seas is an Oasis-class cruise ship built by STX France at the Chantiers de l'Atlantique shipyard in Saint-Nazaire, France, for Royal Caribbean International. With a gross tonnage of 226,963 GT, she is the fourth largest passenger ship in the world, larger than her older sisters Oasis of the Seas and Allure of the Seas, but surpassed by her newer sisters Symphony of the Seas and Wonder of the Seas. Harmony of the Seas is also the second longest cruise ship in the world, being surpassed by Icon of the Seas.