This is bonus cache for completing the History of the Chippewa Adventure Lab from 3 years ago. It is a great adventure lab with great stops along the Chippewa River. I revisited each stop today, and the Adventure Lab is still findable despite almost a year since the last finder.
The coords for this cache are found by doing the Adventure Lab. If you did the Adventure Lab a long time ago and got the bonus https://coord.info/GC9TPNW, the container and the location is the exact same. I am just listing this as a mystery cache because that follows the guidelines for Bonus caches. Also it was confusing to have a traditional cache located in the water, where it is not possible to find a cache.
Booker and Old Abe