Royal Caribbean International has trademarked the name Metropolis of the Seas. The trademark was registered by the cruise line on 01 October 2018.
The trademark is just one of multiple trademarked names which the cruise line has registered in recent months.
In September 2018 Royal Caribbean International trademarked three other names which included Eon of the Seas, Gallant of the Seas and Phenom of the Seas. The name Apex of the Seas was also previous trademarked by the cruise line.
Currently Royal Caribbean International has five ships on order or under construction, four of which are yet to receive names. Perhaps it is possible one of the new ships could be named Metropolis of the Seas?