For the cruise itself, you can bring any size you want. I recommend carrying it on or double ziptop baggie-ing it if you're going to put it in a bag that's checked onto the cruise.
For the flight, you can bring any size as long as you put it in checked luggage. Please please please double ziptop baggie it. If you want to take it in carryon luggage, you'll have to follow the 311 rules.