01 - Combine cubed watermelon and lime juice in a blender. Puree until completely smooth, approximately 30-45 seconds.
02 - Pour the puree through a fine-mesh sieve into a pitcher to remove any fibrous pieces for a silkier texture. This step is optional but recommended.
03 - Divide the strained watermelon puree evenly among 4 tall glasses, filling each glass about one-third full.
04 - Place one generous scoop of vanilla ice cream into the center of each glass, allowing it to rest on top of the watermelon puree.
05 - Slowly pour the chilled lemon-lime soda over the ice cream and down the side of each glass, allowing it to foam up naturally.
06 - Top each float with fresh mint leaves and small watermelon balls or slices for visual appeal.
07 - Serve immediately with a straw and long spoon to enjoy both the foamy top and creamy bottom layers.