The ship has a diesel-electric powertrain using three Azipod azimuth thrusters. Each propeller is driven by a double wound 3-phase synchronous motor of 14,000 kW (19,000 hp) with four-bladed fixed-pitch bronze propellers. The motors are mounted outside the hull directly on the propeller shaft inside the pod. The three propellers are arranged so that the center propeller is a pushing on–azimuthing Fixipod-type and the two wing ones are of pulling-azimuthing–type steering propellers. She has a maximum speed of 24 knots (44 km/h; 28 mph).
Mariner of the Seas has 1,674 passenger cabins.
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.
In 2018, Mariner of the Seas operated cruises from Port Canaveral, Florida to the Bahamas visiting Nassau and Coco Cay. To facilitate re-positioning to Miami, Florida the ship performed three cruises. Firstly from Singapore to Dubai, then Dubai to Barcelona via the Suez Canal and the final leg sailed from Barcelona to Miami.