I usually freeze bread loaf pans for chunks of ice in a cooler. Then put them in a large ziplock plastic bag to keep things dry. This weekend I forgot to freeze my ice ahead. I took a 9 x 13 plastic cake pan, filled it with ice cubes and then water. I put it into the freezer and had a solid ice pack in no time. The lid sealed so it remained dry in my cooler. For the journey home, I emptied the water and refilled with fresh icecubes. Also freeze a wet handtowel. When it thaws works great for clean up.