Well, I think it's perfectly reasonable to bury it, call her and tell her "Tina bar just north of Portland, north edge of the bar, in front of the tree X". Under the premise he wanted her to go get it within a few days or weeks. It was well away from the shore, and I don't think that place was used all that heavily by fisherman, fishermen tend to go to the edge of the water, so I think the chances of it being found by someone else is fairly slim. Hell, if you go with the dredge theory or it washed up there a year or two after '71, it still took several years for anyone to find it, so, "it could be easily found by someone else" is already self-defeating, as under most any theory of how it got there, it wasn't found for years. Plus, I just don't think he would care if it was found or she decided not to go get it, but it's very reasonable to say he wanted her to get it, told her where to get it, and if she was going to get it, it was in a place such that within a few weeks chances of someone else finding it are extremely slim, and if she didn't want it, who cares, chances are low they'd be identified as Cooper bills, and even if they were (they were, as we all know), what can they possibly do about it? Nothing, as history has proven, the money as created more questions than answers.