A fresh pineapple-ginger granita gives this rum drink its slushy texture; the granita is also delicious on its own as a dessert.
In a food processor, pulse pineapple, ginger, coconut water, coconut oil, and honey until pureed. Pour into a 9-by-13-inch baking dish and freeze until completely set, about 12 hours. Scrape granita with the tines of a fork to break apart. For each drink, place 1 cup granita in an 8-ounce glass; pour 1/4 cup white rum on top. Garnish with a strip of pineapple core and serve.