How should I pre-chill a cooler before packing it?

Pre-chill the cooler to prevent fresh ice from melting immediately. If you have freezer space, put the empty cooler inside for 12 hours. Otherwise, fill it with a bag of ice the night before, let it sit 6–8 hours, then dump the melted water and load fresh ice and food. For rotomolded coolers like Yeti or RTIC, you’ll need a longer pre-chill or multiple ice bags.