Pre-chilling your cooler can help it stay colder for a longer period. This step is quick and easy and can make all the difference when you're on hour 12 of a 24-hour excursion! To pre-chill, start by filling your cooler with what's called "sacrificial ice." This is ice that you will only use for this purpose, and you'll toss when the time is up. In other words, this is not the ice that you'll use to cool your food and drinks. Allow the sacrificial ice to sit in your cooler for a minimum of 12 hours. Next, dump it out and replace it with clean, clear ice that isn't wet. Then, you're good to go! Another way to keep your items cold for as long as possible is to pre-chill them in the fridge before adding them to your cooler. For instance, a glass Coke bottle that's already chilled will stay cold longer than a room temperature one. If you stock yours without chilling anything first, then most of the ice will be used up trying to simply make them cold. Pre-chilling skips this step and lets the ice continue that cycle, not start it from scratch.