We’ve come a long, long way in cooler technology in the last decade. Super-insulated, rotomolded coolers are at every campsite you visit these days. There are dozens of manufacturers cranking them out, and they’re pretty good. Packed with ice, these super-coolers keep your food and drinks cold for up to twice as long as old-style coolers.
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But confidence in the technology can make it easy to get sloppy in loading your rotomolded cooler for maximum efficiency. So here’s a refresher course on best cooler practices—no matter the material your cooler is made from.
1. Pre-chill your cooler
That could mean storing it open overnight in a walk-in freezer if you have access. If not, put a couple of “sacrificial” bags of ice inside and close it up tight overnight. Then when you go to pack it the next day, the inside of the cooler is already ice-cold.
2. Always remember: Cold air sinks
That means the stuff you want to keep coldest longest goes in first, so it lines the bottom where the chill will settle. For a typical camping trip, that means frozen solid stuff you won’t be using until later in the trip—frozen meat, vegetables, desserts and other stuff like that.
3. Fill empty space with stuff you’ll use
A cooler full of cold stuff stays cold better, and a partially filled cooler has airspace to take in the warm air every time it’s opened. A smart way idea: Freeze some water bottles as ice pack and space fillers and for hydration as they thaw. 
4. Put your “primary” ice on top of the frozen food
Big pieces of ice melt slower than cubes, so use block ice whenever you can. A couple of big blocks with frozen water bottles filling the gaps are optimal.
5. Next layer: the food you’ll access more often
Things like condiments, hot dogs, cheese, butter, eggs, bacon and milk—stuff that will be in and out several times a day.
6. On top of the essentials layer, put an insulating mat
It might be a piece of a wool blanket, an old foam sleeping pad or something similar. It should be cut or folded to custom-fit as well as possible inside your cooler. Then when you open the lid to grab something, just lift up enough of the insulating mat to find what you’re after. When you’re done, drop the mat back in place. You won’t believe what a huge difference this makes in keeping the cold in and warmth out.
