While I truncated your post the point made remains. Before one can print their boarding pass you agreed to the Ticket Contract found here:
https://www.carnival.com/about-carnival/legal-notice/ticket-contract
"Carnival may change the duration and/or itinerary of the cruise at any time. The Vessel shall be entitled to leave and enter ports with or without pilots or tugs, to tow and assist other vessels in any circumstances, to return to or enter any port at the Master’s discretion and for any purpose, and to deviate in any direction or for any purpose from the direct or usual course, and to omit or change any or all port calls, arrival or departure times, with or without notice, for any reason whatsoever..."
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