My friends have a home near here. They checked the navigational charts for Lake of Bays, but couldn't find a name for this tiny island. So I am naming it after the Czech composer Zdenek Fibich.
We play piano quartets at my friend's place on Lake of Bays, and we played Fibich's underrated quartet the day I hid this cache. Appropriately enough, the functional part of the cache was constructed from a tube meant to hold viola strings.
A few words about the hide and location: It would be tough to dock anything larger than a canoe on this rocky isle. I paddled a canoe to get over here; it you were in a larger boat, you may have to swim the last 50 feet or so. Bring your own pen and also a tweezers. I included a hint in encrypted text. The hint is a total giveaway; I would hate to have someone come all the way out here and not find this.