@@cameranmanner4701 Well, that is a science question with a bit of mathematics. If something will float over the water, it must have a density lesser than one g/cc. The 35L cooler has a rough dimension of 40 x 40 x 30 cm or a total volume of 48,000 cc (why not 35,000 cc? I am just confused, sorry). Then we could put in anything lighter than 48,000 g (48 kg; seemed unbelievable), and the cooler will still not get sunk. To be on the safer side, anything more delicate than 35 kg is more likely.
i think you could use it for storing food during transportation, depending on amount/size of the food and duration it takes for delivery. just make sure you have enough ice packs.