Maximizing ice retention time can be done by following these steps. First, you’ll want to be pre-chill any food or drinks you plan on storing in the cooler. Second, you’ll want to use approximately a 2:1 ratio of ice to food/drinks. This will maximize cooling and keep your stuff cold for longer. Third, you’ll need to keep your cooler away from direct sunlight and refrain from opening the cooler too often. And finally, you’ll want to use larger sized ice blocks. Larger ice chunks will melt slower than smaller ice, so if you can get your hands on blocked ice, it will last much longer.