I just saw this...
I have seen shops in the Caribbean devoted to voodoo - just as I have seen them in New York City.
I believe voodoo originated in Haiti which is a pretty insular culture. You may find some shops in the Dominican Republic or Puerto Rico with voodoo candles and other icons.
But if you think you are going to see people doing voodoo rituals in the Caribbean, especially during the daylight hours when the cruise tourists are there - probably not going to happen.