Mariner of the Seas is one of five Voyager-class cruise ships of Royal Caribbean International and can accommodate 4,252 passengers.

[1] In early 2018, after a month long refit costing US$120 million which included adding additional cabins, the ship's gross tonnage was increased to 139,863 from 138,279.

[6] In 2018, Mariner of the Seas operated cruises from Port Canaveral, Florida to the Bahamas visiting Nassau and Coco Cay.

[7] During the coronavirus pandemic, the Miami Herald reported that, after cruises were cancelled worldwide and they had disembarked all passengers, Royal Caribbean Cruises had refused the CDC rules to repatriate many of their crew members due to the associated costs, with many crew members turning to desperate measures, such as hunger strikes, as a result.

[8][9] On 10 May 2020, a male Chinese crew member of Mariner of the Seas was found dead aboard the ship.