<p>Royal Caribbean has just annouced it has ordered a fourth Oasis class ship. This announcement came during the keel laying ceremony of the third Oasis class vessel in STX shipyard in Saint-Nazaira, France. The ship is expected to enter service in 2018.&nbsp;</p><p>The Oasis and Allure of the Seas are currently, by far, the largest cruise ships in the world. They will be joined by 2 more the coming years. It is expected that the next two vessels will be about 20% more fuel efficient.&nbsp;</p><p><br></p><p>For a list of cruise ships entering service the coming years, click <a data-cke-saved-href="http://www.cruiselegend.com/NewShips.aspx" href="http://www.cruiselegend.com/NewShips.aspx"><span style="color:#0000CD;">here</span></a>.</p>