3 cups watermelon, cubed and frozen, 1 ripe banana, peeled and frozen, Zest from

3 cups watermelon, cubed and frozen, 1 ripe banana, peeled and frozen, Zest from

3 cups watermelon, cubed and frozen, 1 ripe banana, peeled and frozen, Zest from 2 limes. Juice from 2 limes (about 4 tablespoons), 1/2 cup water.