Place the watermelon cubes in a blender and blend until smooth.

Strain the watermelon puree through a fine mesh sieve into a large bowl or pitcher to remove any pulp, if desired.

Stir in the freshly squeezed lime juice and sugar or honey (if using) until fully combined. Adjust sweetness to taste.

Just before serving, add the cold sparkling water or soda water to the watermelon-lime mixture. Stir gently to combine.

Fill serving glasses with ice cubes and pour the watermelon soda over the ice.

Garnish with fresh mint leaves and lime wedges, if desired.

Serve immediately and enjoy the refreshing drink!