Most coolers stop being cold after a day because people throw bagged ice on top of room-temperature drinks and call it good. The trick is dry ice on the bottom, regular ice as a barrier on top of it, and contents stacked above. Done right, your cooler stays freezer-cold for 2-3 days even in summer heat.
Keesman from Eastmans Hunting Journals walks through the technique he uses on multi-day antelope hunts. The principle is simple: dry ice does the heavy cooling, regular ice insulates your drinks from getting frozen solid, and stacking order controls what stays coldest.
You'll need a quality cooler (Yeti-style or similar), 1-2 lbs of dry ice in a paper sack, 10-20 lbs of regular ice, and 5 minutes to pack it.
Frequently asked questions
How much dry ice do you need for a weekend?
Around 1 to 1.5 pounds for a typical 45 to 65 quart cooler on a two day trip. More than that is not better, because everything above it just freezes harder rather than lasting longer.
Is it safe to put dry ice in a cooler?
Yes, with two rules. Never handle it bare-handed, since it sits near minus 109F and causes frostbite on contact, and never seal it in a fully airtight container, because it turns to gas as it warms and needs somewhere to vent.
Why cover the dry ice with regular ice?
The regular ice is an insulating barrier. Without it, anything resting on the dry ice freezes solid, which is how people end up opening a cooler full of burst soda cans.
Why does the cooler need to sit for an hour before you open it?
The interior has to stabilize. Give it an hour and the ambient cold pulls down everything you packed, including the room-temperature items you added last. Opening it early just lets that work escape.
Does it matter if a cooler is only half full?
It does. Empty space is space for warm air to move around in, so a packed cooler holds temperature far longer than a loose one. Fill gaps with extra drinks or even crumpled newspaper if you are short on food.
