Fill a glass with ice.
Pour in the rum and the pineapple juice. Mix.
Next pour in the pom wonderful gently and it should slide down to the bottom of the glass.
If you like, pour a shot of dark rum on top of the pineapple juice by pouring it slowly over an upside down spoon that is just touching the edge of the glass.
Top with a wedge of pineapple and/or a cherry.