Agree with many comments - carry on, polar bear cooler, no ice needed - fill all air space. I have cooked spaghetti and frozen it to fill the spaces - It holds a lot of 'legal' water (ice) and is (cheap) disposable if it melts too much or gets crushed. I use the spaghetti (in baggies) across the top and around the sides as I have space. Linguini is another alternative... ;-)