What's up with the floating Xmas tree?

We were driving on that beautiful, but barren, stretch of waterfront parallel to Bay Street when we saw (what looked like) a mysterious floating Christmas tree.

Because of unnamed impediment (read: laziness) we didn't take a pic, but thanks to @GirlontheFerry we now have visual proof of this holiday miracle.

Driving by, we thought the 'tree' was placed on a dock, but the image clearly shows water between us and the ornament. Weird. Who put it there? How does it float? (cue: double rainbow) What does it mean? The world may never know.

Area of detail (in case anyone wants to swim out there and check it out):