So tagging onto this thread instead of a new one. Has anyone used the combo check in option at the Port of Barcelona? The airport states that you can hand your bags over at the port and they will go to the airport. Not available for all airlines but American is one of them.
"For passengers from a cruise and must to take a flight at Barcelona airport, Barcelona port facilities have 16 check-in desks intended for this operational Port-airport. The luggage is transferred directly to the airport, controlled by the automatic baggage handling system."