Fitz:
Your comment about otters loving canoes prompts me to report a little incident from a couple of days ago. At the end of a warm afternoon of work, I walked down to my dock, stripped off and jumped in for the short, 20' swim to my raft. The dog stayed behind, on the end of the dock, beside my overturned Chestnut.
On the way back from the raft, I kept hearing short 'wooshing' noises behind me, but assumed (without looking) that it was just waves slapping up against the raft. When I reached the ladder at the end of the dock, I noticed the dog was intently gazing at the water behind me. I turned to see a fairly large otter swimming back and forth about 10-12' away, snorting as he went between me and the raft as if wanting to play. I exited rather than wrestle in the waves, while he continued to swim between dock and raft.
My raft seems to attract wildlife: I found three otters one day, all curled up together and sleeping contentedly in the sun. I have had as many as five hen mergansers doing the same thing. And a blue heron (see photo).
Not sure though that 'wave wrestling' with otters is a recommended activity. Two years back, the neighbor's dog, a Lab cross, decided to jump in and play 'otter tag'. They thought it was great fun, and almost drowned the poor dog, who was only saved when the neighbor went in, fully clothed, to rescue the mutt. One otter had him by the tail, another by a leg; between them, they were slowly dragging him down. I figured I didn't need any old otter lunging after my dangling bits, trying to pull me under.