Note: Make sure the base of the ice cream maker is frozen overnight before making this recipe. 

1. Chop the watermelon. Place the watermelon, sugar, lime juice, and ice in a blender and blend until a smooth juice forms, then add ice and blend again.
2. Pour the mixture into an ice cream maker and freeze for 20 to 25 minutes. The texture will be icy and creamy at this point. If desired, place in a container and freeze for 1 hour for a harder texture that forms into scoops. You can freeze up to 2 hours day of (stir before serving). Freezing overnight makes a very icy texture. If you have leftovers the next day, allow them to sit at room temperature for about 20 minutes. To improve the texture, you can pulse in a blender or food processor if desired.