Pre-chill everything and add a buffer layer.

Yes, you can prevent freezing by pre-chilling everything and putting a barrier between the ice and your food.

The problem is direct contact — ice packs or dry ice touching items will freeze them fast, especially if the cooler is empty around them. So pre-chill your food and drinks before they go in. Cold items take longer to cool down further than warm items. That alone buys you time.

Next, separate the ice from the food. A layer of cardboard, a towel, or even a few inches of newspaper works. This slows the cold transfer without sacrificing overall temperature. If you’re using dry ice, wrap it in newspaper or a cloth — it’s way too cold to leave bare.

Also, don’t overpack with ice. You usually need less than you think. A 2:1 ratio of food to ice is fine for most day trips. More ice just means more cold and more freeze risk.

Better to have a cooler that’s a few degrees too warm than a frozen salad.