Bleach is the fastest way to kill cooler mold.

Yes, but use diluted bleach, not soap. Mold gets into the pores of the plastic, and soap just makes it smell like a wet gym bag. A tablespoon of bleach per gallon of water, scrub the whole thing, let it sit for five minutes, then rinse like crazy until you can’t smell bleach anymore.

White vinegar also works if you’re anti-bleach, but it takes longer and the smell lingers. Avoid scrubbing with anything abrasive—scratched plastic is a future mold magnet. The biggest mistake people make is not drying it completely afterward. Leave the lid cracked for a day in the sun, or hit the inside with a towel and let it air out.

Future you will thank you for not smelling mildew next time you pack a picnic.