Add pineapple, coconut milk, pineapple juice, and ice to a large blender. Blend until smooth.
Divide mixture into 4-6 glasses.
Top each glass with ½ to ¾ cup of carbonated water along with a wedge of fresh pineapple.
Notes
If you're making these into adult-only cocktails, add 2 ounces of coconut rum to each glass before pouring in the coconut-pineapple mixture.If you don't have a blender, you can easily mix these up over ice instead of blended!