Puree the watermelon in a blender and measure out 4 cups of liquid; reserve any remaining puree for smoothies or ice pops.

Whisk in the Palm Breeze and salt until dissolved.

Transfer the mixture to a 9-by-13-inch dish and freeze for 4 hours, scraping the mixture with a fork once every hour to create small flakes. The granita can be frozen, covered, for up to 1 week.

Scoop the granita into chilled glasses as needed and serve immediately.