Keeping food cold when camping is essential! Unless you're backpack camping, you will want or probably more likely need ice. Keeping foods such as meats, fruits, yogurt cold is a necessity and of course keeping your beer chilly may be a priority for some as well. I know it would be for us! Oh and of course chocolate milk for my youngest.
A cooler is essential for keeping your items ice-cold. A day or two before we leave for a camping trip, I usually take a 6 to 12 bottles of spring water and put them in my freezer until frozen solid. Then when we pack up our cooler, we use the frozen ice bottles to keep everything ice-cold. Depending on the type of cooler you are using, it could take a day to a few days for the ice to melt in your bottles. When this happens, it's going to be time to find a local store buy bags of ice.
We have a 100 quart Coleman Cooler which says it keeps ice up to 5 days in 90 degree weather days. I will actually concur that it does keep ice for a quite a few days however most of the ice does melt, however even with that being said, the water is ice-cold and difficult sometimes to plunge my hand into the icy cold water to fish out a juice box. There is a spigot on the bottom which makes emptying some of the water out so easy! We paid close to a hundred dollars for this cooler but it has definitely done its job in keeping everything ice-cold.
Last year we upgraded from tent to pop-up trailer so now we have a little mini refrigerator in our camp as well but we still use our cooler and we still buy lots of ice bags for it for drinks and things that won't fit in the refrigerator. Yet, we still find ourselves buying many bags of ice from the local store or gas station a few days into our trip especially if it's a week or longer. "Throw another bag of ice on" or "Yah we could use a bag of ice" are both statements we find ourselves saying often. I have considered purchasing a portable electric ice maker, such as Gourmia GI120 Compact Portable Electric Ice Maker, but have yet to take the plunge.