2. Prep and refrigerate your food and drinks.
First, remove unnecessary packaging, including styrofoam and cardboard, to reduce weight and save space. Assume that store-bought packages will leak, and place any items that aren’t airtight into well-sealing food storage containers, jars, or plastic or silicone bags. Opt for the smallest containers possible to minimize air and increase contact with the ice. “We put raw meat in watertight Tupperware with a gasket to minimize contamination as things move around and melt,” says Megan McDuffie, co-founder of camp cooking site Fresh Off the Grid.
If potable water is scarce at your destination or if you’re planning to pull over and eat on the way, wash your fruits and vegetables and prep your snacks and meals as much as possible before packing them up.
Stash everything you plan to carry in the cooler in the fridge or freezer 24 hours before the trip. “Anything that we put in the cooler needs to already be cold,” McDuffie says. “The cooler is meant to keep things cold, not to get them cold.”
3. Pick the right size cooler.
You’ll need about two-thirds ice to one-third food and drinks to ensure that everything stays at or below the U.S. Food and Drug Administration’s 40 degree Fahrenheit recommendation, which is critical to prevent bacterial growth. You may need to change your cooler size or use more than one to get the ratio right.
The FDA recommends packing drinks in a separate cooler so your party can repeatedly open it without dinner getting too warm and going bad. If you’re traveling with kids, consider using a smaller cooler or lunch box for their snacks and drinks so they can easily help themselves. “A cooler’s ability to keep ice cold is a direct function of how many times you open it and how long you open it,” says Fresh Off the Grid co-founder Michael van Vliet.