To make these, gather all your ingredients: watermelon, light rum, club soda, mint, lime, and a sweetener. I prefer agave over simple syrup, to taste. Make a mojito as you normally would. Top with club soda, but only to fill about 1/2 the cup. Then, cut watermelon into chunks and blend to create a puree. Fill the rest of the cup with the blended watermelon, stir to blend, and garnish with a watermelon wedge. Yum!