Grease one 10x15 inch baking pan. In a large saucepan over medium heat, combine the sugar, corn syrup and water; bring to a boil, stirring constantly until sugar is dissolved. Continue to cook, without stirring until a candy thermometer reads 300 degrees F (150 degrees C). Remove from heat;
stir in butter, vanilla and baking soda. Add cereal and cashews; pour into prepared pan and allow to cool.
Break into pieces and store in air tight container.