Maybe I should have posted it here,but check my post on the advice board and please let me know what you think.
Turtle
My opinion
If you are careful about not getting food smells on the outside of that container, you shouldn’t have to go to an extreme measure like submerging your food. Take a little pine sol along, lightly wipe the outside of the container with it every evening and rinse, and set it off from the campsite. Would I risk submerging my entire food supply for the trip - No. I would be especially concerned about otters that will investigate and chew on anything that is on shore, floating, or submerged. But I think your concept has some merit for a very small size container for short term storage of fresh meat and other perishables. If you could sink that sucker below the thermocline in a deep lake you could have a very satisfactory makeshift icebox.