If you only plan on going to the Caribbean Islands for the next five years, do not waste your money on a passport for your children. If you think you may need them because you plan on touring Europe with you children then purchase one. The Caribbean Islands do not require passports. While departing the Magic in Jan., I asked this question from the custom officials. They said they would not spend the money for their children if only going to the Caribbean. BTW, I also asked about my passport because it will expire 6 weeks before next years cruise. They said they would accept it as a form of identification for a Caribbean cruise since they do not require passports.
I was scheduled to go on one of the repo cruises but had to cancel because my daughter's school changed the start date for school. At that time I e-mailed Disney if I would need a passport for the cruise and was told no. That was 4 months ago.