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Don't book that flight. Your ship "arrives" at 7am but that doesn't mean you can leave the ship at 7am. The vessel still has to be released by Customs and that can normally take an hour or more before they allow passengers to debark. It is realistic to expect that you won't be allowed off the ship until 8am or even 8:30am. This means you will not be able to make a 9:15 flight. Actually, trying to make a 9:15 flight for any cruise is unrealistic.