I had an interesting idea of what it COULD be.
I was thinking that perhaps it's not something going into the water, but rather something is coming out of the water.
The dark object to the right reminds me of the structure of a wing. The object looks too small to be a smaller bird like a loon, but maybe big enough to be a pelican or herring?
In all honestly, I'm not sure what it is, but it doesn't look like a log.”
After studying the image the author/investigator feels that the top area of image could possibly be a ridged dorsal fin and there appears to possibly be an eyeball, nostril and mouth in the front lower right portion of the image. (See image # 6)