At least 4-6 hours before you wish to enjoy your popsicles, add all ingredients to a blender and blend on high until smooth and frothy. Taste and adjust, adding more watermelon or coconut water for sweetness or more lime for brightness.
Add the mixture to a popsicle mold (we used this one) and add popsicle sticks. Freeze until firm — about 4-6 hours. To remove from molds, let thaw slightly by setting at room temperature for 10 minutes or dipping mold in warm/hot water to help loosen.