PLACE graham squares, side by side, in single layer in ungreased 15x10x1-inch baking pan.
MICROWAVE caramels and water in microwavable bowl on HIGH 2 to 3 minutes or until caramels are completely melted, stirring after each minute. Pour over grahams; spread to evenly cover graham squares.
SPRINKLE immediately with marshmallows, chocolate and peanuts; press gently into caramel mixture with back of spoon to secure. Cool completely. Cut into 24 squares to serve.