Muddle lime and lemon wedges in the bottom of a 12-ounce glass. (Don't over-muddle the fruit; it will make the drink bitter.) Fill glass with ice. Add coconut water, cranberry juice, soft drink, and simple syrup. Stir well, or pour into cocktail shaker, and shake well. Serve immediately.
To make simple syrup: Stir together 1/2 cup water and 1/2 cup granulated sugar in a small saucepan; bring to a boil over high. Remove from heat, and cool completely. Pour cooled syrup into an airtight container. Store in refrigerator up to 1 week.