Rich the Bushwhacker: Time to let this one go.
It was out in the floodplain for 5 years, and there were two floods in that time where the water was up a couple feet over the location. the tether approach worked great, the container stayed in place for the entire time it was out there.
Revisiting the location, A lot has changed, the path along the river is completely gone. I'm not sure if the river took it, or the deer in the area just blazed a newer path inland.
Cuts in the river bank have changed over time. when originally put out, there was a cut just north of the cache feeding the swamp area, In the last flood, a new cut appeared 500 feet south and the old one north of the cache gradually filled in. This changed the preferred route to the cache, making the direct route much easier.