You do need to declare dry ice, but you are allowed up to 5 pounds without any additional headache. Other posters are right on though...just use some el cheapo frozen vegetables instead. I'd advise against styrofoam coolers as they are relatively easy to break. If you have a small plastic cooler handy then use that. Otherwise, just wrap the frozen food item with the frozen veggies, bundle that up with an old blanket (super tight), and then put it in a cardboard box and check it.