Cut the watermelon into chunks and puree in batches in the blender. Strain the watermelon with a fine mesh strainer, pushing on the pulp with the back of a spoon to remove all the juice. Discard pulp.
Pour watermelon juice and strawberry mineral water into a pitcher. Add the juice of one lime.
Serve each drink over ice with a few blueberries in each glass.
Notes
Use whatever flavor sparkling mineral water that you like. You can use unflavored if you wish!If you don't care about pulp in this drink, you can skip straining the pulp from the watermelon juice.