Combine the watermelon cubes, mint leaves, lime juice, and honey in a blender.

Blend until completely smooth, about 30 seconds.

Strain through a fine mesh sieve into a pitcher for a smoother texture, pressing on the pulp, or leave it textured and skip this step.

Cover and refrigerate the watermelon base for at least 1 hour, until well chilled.

Fill glasses with ice and divide the watermelon base evenly among them.

Top each glass with chilled sparkling water and stir once gently.

Garnish with a small watermelon wedge and a mint sprig, and serve immediately.