Well actually Panama is at the bottom of Central America that is much closer from South America than North America, and the drinking age there is 18. The problem the RCCL don't designate specific drinking age for cruises leaving ports on Central America. Since it's a non-US port and the ship don't cruise near any US city I would assume it's 18.
Had anyone already travelled on the Grandeur of the Seas? What are your thoughts on the ship?