Place the watermelon on a flat surface and slice off a piece of the rind on the bottom to create a flat surface for the punch bowl to stand. Be careful not to cut into the flesh or your bowl will leak. If using mini watermelons, slice in half to create two serving bowls.
For a large punch bowl, lay the watermelon flat on its side and cut a large oval opening in the top (like a pumpkin). Scoop out the watermelon flesh leaving a bit of pink around the sides and bottom.
Place the watermelon flesh into a blender or food processor and puree for one minute. Pour the puree through a fine-mesh strainer, over a large measuring cup, to remove the seeds and pulp. Lightly press with a silicone spatula to push all of the juice through. Don't forget to scrape the underside of the strainer as well.
Pour the watermelon juice, rum, orange liqueur, pineapple and lime juice into a large, ice-filled glass pitcher and stir to combine.
Pour cocktail into ice-filled glasses from the pitcher or ladle from the watermelon bowl. Serve garnished with a pineapple wedge and pineapple leaves, or watermelon wedges.
Notes
This cocktail makes approximately 6.5-cups before added to the ice. It can be more or less depending on how juicy your watermelon is.
Change things up and try a flavored white rum like Malibu coconut, peach, lime, or passion fruit.
I decided to go a bit rogue and poured all of the ingredients back into the blender to create an icier, frothy cocktail. It is delicious either way!
To make ahead of time, combine all of the ingredients except for the ice in a large pitcher or container. Cover and chill in the refrigerator until ready to serve.
If you have leftover watermelon punch, place back in the refrigerator for up to 3 days. For longer storage or between parties, pour into a large zipper topped freezer bag, squeeze out the excess air, and place in the freezer until needed.