Could you use a 5 gallon oil bucket from a restaurant, lightweight, durable and watertight.
Can you get your food flown in already in heat sealed bags? You don’t have to worry about a perfectly sealed food locker then. I used them for camping and you don’t have to worry about water getting into anything.
No 
And I still think the zeer is the way to go.
RE: dryness in Canada, the farther North you go, the less humidity you get. Also above the 60th parallel, where I happen to live, humidity is usually below 20% from October to March.
Oh, we are definitely going to try out the zeer, we will make one and test it out to see if it will work, I think it’s a brilliant idea.
And I think I’ll be trying the luggage suggestion. My husband suggested old bowling balls cases, which we often see at the second hand store. With a few holes drilled to let in the cooling water, they seal tightly, durable and round to bounce off the rocky lake bottom and have handles to easy attach the rope. You might need more than one, and you may need to weight them, but that’s what I think I’ll try first.
Thank you for all your suggestions, I will definitely let you know how the zeer tests when we get all the parts together!
The OP keeps talking about keeping his mayo cold for a couple of days. Why not just give it up for you trip. It’s really not that healthy.
For things like tuna fish salad, it’s easy, makes a nice lunch. But the suggestion to use the little packets is what I think I’ll go with, I just need to source out a supply!
For instance, if my food delivery arrives, I’d like to get a pound of bacon. I don’t really want to eat it all on the first day. If I could keep it a day, or even two, that’d be awesome. I like garlic butter, very handy for cooking lots of campy things, like dried pasta, fresh caught fish, garlic bread, etc. It doesn’t need to be cooled a lot, like a fridge, I believe, just enough to keep it from going off. Same for Parmesan, great on lots of really basic foods, but sure to go off in the heat. Again, just a little cooling would go a long way. A whole watermelon, same thing. I can’t eat it in a day, but it’s going to turn pretty fast, if it’s hot.
The lake is actually pretty chill in the shaded deep spots. I think it might be enough. I could be wrong, of course, but I’m going to give it a try and see.
The crisp of fresh vegetables will be sorely missed, I’m sure. With a little bit of chill, I’m thinking I could keep things like cucumber, carrots, celery, green onions and cabbage. It’s not a vast selection of greens, but it’s enough to get by, I’m thinking, for a couple of months.
Bread will be tricky too, for a few days after being restocked it will be a treat, the rest of the time it may be bannock. Guess that’s what I’ll research next.
I recommend a canvas bag, and packing the food itself in ziploc bags. Because canvas will get wet, the cooling effect will be better than a plastic drum with air inside.
Because it will sink, you will need a good rope to haul it out again.
I’m afraid it won’t withstand the rocky lake bottom on retrieval, if it tears or gets stuck, you’re sunk. I have considered it though.
Bacon and Parmesan really shouldn’t be going off in a few days, they’re both preserved foods. Unless you’re getting *ersatz *versions of both.
Likewise, garlic butter might be iffy, but garlic and butter separately will last just fine. Just mix them together when you’re making the garlic bread.
On the humidity point, even if Canada in general is pretty dry, it might be more humid in the immediate vicinity of a lake.
And if you’re getting deliveries of frozen food, can you get deliveries of ice, too? That would seem to me to be the simplest.
While thinking about this I started wondering – if you had frozen food you wanted to keep frozen as long as possible, would it be better to sink the food container into a cold lake, or to keep it out in the warmer air? The water, being colder, should transfer less heat into the food, but it’s a lot denser than air – will that affect how fast the frozen food heats up?
In my experience, when I’m trying to partially thaw a frozen plastic bottle of Vons Apple Cider Sparkling Water Beverage to turn it into apple cider slush, the ice melts faster when I submerge it in hot water at 140 degrees F than when I put it in the oven at 225 degrees F. I always assumed this was because the much greater density of water (when compared to air) meant that there were a lot more hot molecules colliding with the cold plastic and heating it up than there were in the air, even if the temperature of the air was significantly higher.
So … would you be better to dunk it in cold water with little insulation, or keep it out in the air but as insulated as possible? (Until it heats up to the temperature of the water, at which point it seems obvious that putting it in the water is the best option, so it won’t continue heating up… right?)
I understand what you are looking for and I’ve yet to find one myself. “Waterproof” coolers are meant to keep melted ice from leaking out - and they rarely succeed in their goal (in my experience).
You want something weighty enough to sit on the bottom of a cool/cold lake. I would think that a good rubberized wrapping around the seal on a classic cooler would do the trick for waterproofing. That should be easy enough to find. But there is an air issue which will cause a problem. Air is not only part of the insulating layer of the cooler, but air will be inside the cooler too. You’ll need to make it heavy enough to sink below the surface of the lake despite the airspace inside the cooler. And you don’t want something that can rust.
I don’t think anything commercial out in the marketplace will satisfy your requirements.
When I mentioned this I meant this type…
I am pretty sure it would work.
Water is a better conductor than air, which means hot water will heat things quicker than hot air, and cold water will cool things faster than cold air.
So while using air first for isolation, and then water for cooling down once the isolation is gone would be the ideal method using specific properties, in practice this would require checking every 15 or 30 min. on the temp. to determine when the isolation has worn off. So putting the food in the cold water to start with would be less trouble during a trip, I’d think.
Are you worried about cryptosporidium and giardia? If so, you’ll want a semi-truck full of iodine tablets to disinfect the lake.
I’ve drunk boat loads of water from this lake with no ill effect, so I’m not too worried. In fact a large community of people, well spread out, drink nothing but water from this lake and suffer no ill effect, so I’m thinking it’s okay.