Dry Ice

[Kauri]

I haven't had much experience with dry ice, but what has worked great for us for keeping things cold is double-bagging regular ice in two gallon ziplocks rather than just having it loose in the cooler. We recently purchased a new multi-day big cooler (from Canyon; it's a big improvement over our three smaller 25+ year old Igloo coolers) and that definitely has helped keep things cold longer. They also suggest pre-cooling the cooler with a bag of ice before using it on a multi-day trip.