Mountain Minstrel wrote:
.... he puts his food in a waterproof bag with a rock, ties it to a rope, and tosses it into the lake.
I assumed that this meant that the bag (?) of food was tossed into a relatively deep part of a lake, in which case, it would indeed be very unlikely that a bear would dive for it. Could one be so dexterous as to "reel in" the cord? ... or clever enough to simply hold onto it, and walk/haul the bag of food to shore? Perhaps, though burying the cord would help.
Almost There is correct about the bear's great sense of smell, yet it is also true that their testing of potential new food items is simply adaptive behavior. In Alaska, and elsewhere, bears are known to bite into most anything new- unfortunately, this includes float plane pontoons, oil and gas cans, met station equipment, kayaks, buoys, ... and pretty much any can of anything- including all of your beer! They seem to enjoy/or be intrigued by anything that provides resistance. This could again be a sort of adaptive behavior, since their chewing into natural things like tree trunks, rotten wood, hard fruits and nuts, and strong smelling items like hives has proved valuable to them. I think it is equally possible that for bears that have been around humans, they have learned that it is well worth testing out human items as likely sources of rich new food.
My dry-bags are certainly lighter than full-sized bear cans, but would they really prove water-proof if stored overnight in deepish water? If it really worked, it would usually be as easy as creating the perfect bear-hang in a tree or off a cliff- neither of which I used to rely on. In the years before bear cans, I always "defended" my food, and have never lost so much as a peanut.
Thanks for the interesting idea, and for the humor!

The Harlens.
Properly trained, a man can be dog’s best friend.