The first two ships in the class, "Oasis of the Seas" and "Allure of the Seas", were delivered in 2009 and 2010 by STX Europe Turku Shipyard, Finland. The third and fourth ships in the class, "Harmony of the Seas" and "Symphony of the Seas" were built at Chantiers de l'Atlantique in Saint-Nazaire, France. Royal Caribbean International, in conjunction with USA Today, sponsored a contest to name the first two vessels. On 18 February 2019 Royal Caribbean announced the order of a 6th Oasis class vessel from Chantiers de l'Atlantique for delivery in 2023 with a double occupancy of 5,714 and gross tonnage of 231,000.