Cruise Wedding Gift Ettiquete

I wouldn't say anything. 99% of your guests will probably not bring a boxed gift. They might give you money, but I would assume most will mail gifts and or money to your house after the fact. They will also understand that you have limited room to transport things. The vast majority of people aren't so stupid that you would need to point that out to them. I also think it is never appropriate to discuss gift preferences. If someone asks, just say something like we don't really need anything for the house but we are saving up to buy a bigger place.

I would just tell people, "Unfortunately, Carnival does not allow gifts on board due to US customs. If you want to gift us from the registry, you can have it sent to our home before or after the wedding. Or you are welcome to contribute towards our savings for a new home."

But I would certainly want to know that a boxed gift could be confiscated, I'd likely just have something shipped to your home instead.

This is actually one of (if not the only) reason you can put something about gifts on your invitation. you could just say something reeeeeeeally generic...

"Due to customs restrictions (laws, whatever), bags or boxes over SIZE/WEIGHT/WHATEVER will not be allowed on board"

Thanks everyone!