If you drain the water off the cooler as it melts, the inside will actually stay colder. I usually stick my cooler, open, in the chest freezer when I start to pack. When I get to the food I pack it in ziplocs or vacuseal bags and put it in the cooler then the ice on top of it. If it doesn't need refrigeration it goes in a box (a lot of people seem to think a cooler is for everything). I also leave frozen anything I'm not going to eat on day 1. Then on-site I try to keep the cooler in the shade and drain the water at least twice a day and if possible make a run for more ice at some point. I've taken fish out of the river on Saturday, buried the filets under the ice and had them freeze in the cooler in four days of sitting there. The cooler's a nothing special Coleman that's about 10 years beat. Serious though - get rid of the water as the ice melts, the cooler will stay colder.
