My sister traveled with oxygen. The airlines require you to use their oxygen (for a fee). She had a machine that "made" (?) her oxygen - quite a large thing that plugged into a wall and have a very long hose, and which was also used to fill her smaller temporary tank. On the last three cruises she did (on Celebrity), she booked a suite, which gave her the room she needed for her machine, which she brought with her. Even if using a great cruise specialist, I would suggest contacting the cruise line personally to make sure you understand all of their (the cruise line's) requirements. Get it in writing from them.