Spread sugar in small dish. Brush rims of 4 margarita glasses with 1 tbsp (15 mL) agave syrup; dip rims in sugar.
In blender, combine ice cubes, Allen’s cranberry cocktail, coconut water, lime juice and remaining agave syrup; pulse until combined.
To serve, pour into rimmed glasses.
Tip: Substitute superfine sugar for coconut sugar if desired.