There I found the following terse summary:
Foreign national boaters are not permitted to enter Canadian waters unless exempted. Failure to comply with the current prohibition of entry for discretionary or optional reasons (leisure, pleasure fishing, sightseeing, etc.) may result in severe monetary penalties or criminal conviction and/or imprisonment. Visit Transit through Canadian waters for more information.
Considering the possibility of being convicted as a criminal and imprisoned, my enthusiasm for visiting Canada has been greatly reduced.
On the other page referenced above, I found the following.
Transit through Canadian waters
You currently cannot enter Canadian waters for optional reasons, such as:
- pleasure fishing
You may still navigate through international or Canadian waters while in transit directly from one place outside Canada to another place outside Canada, if the transit is:
- by the most reasonable route
I am further worried that if I strayed over the border on the water, then making a U-turn to immediately exit Canadian water would NOT meet the above listed criteria.