Pineapple–Lime Agua Fresca

For the simple syrup, in a small saucepan combine sugar and 1 cup water over high heat and bring to a boil. Cook until sugar dissolves. Remove from heat and let cool completely.
In a blender combine 1/4 cup of the simple syrup, pineapple, lime juice, water and ice cubes. (Reserve remaining simple syrup for other uses) Blend on high speed until smooth.
Pour into chilled glasses, and serve.

Remaining simple syrup can be chilled and used to sweeten other fresh fruit juice drinks and cocktails.