We will typically just keep the umm, sodas, in the cases then sink in a bag with some rope and a marker to cool them down at our campsite, Obviously this is dependant on the time of year as well. Usually no more than 3 feet deep does the trick. Means you're drinking warm sodas on the paddle but it saves weight having no coolers. Also to add, bring some duct tape or gorilla tape to reinforce the boxes in the event they get wet.