Dry Ice or Freeze the meat, Freeze your water, Freeze your butter, juice etc. Don't open the cooler unless necessary. Keep in the shade and maybe even throw a blanket over it. A group of us guys used to camp on the Islands in Lake George and never had a problem. It was also summer when we went. Always had cold drinks and food. Just eat what thaws first. But even after it thaws it will still stay good for a few days. Igloo marine coolers are great, wish we had them back then.