Come to Colorado
If she can't quit for a week or two, she is an addict, and you may want to consider that. Addicts generally put themselves in stupid situations, or convince others to do idiotic stuff for them....such as attempting to buy things they shouldn't in foreign countries. Bringing it on board ship can be a felony. In Nicaragua, the sentence for even a scrap is 2 years in prison...not US prison, hard prison.
Many other Caribbean countries are equally as harsh. I've lived in Central America and the Caribbean, and seen people that thought they wouldn't get caught pay a very high price. Even buying it can be risky, a friend got beaten and robbed in Belize trying to buy. So if she can't stop smoking, I suggest you take a closer look at her, and decide if an addict is worth risking things for. If so, go right ahead. I mean shit, it's a cruise/vacation? She needs to numb that out? wtf lol.