It's a Poker Run charity event. They come from all over to participate. They trailer their boats in. None of these boats are situated on this river....that I know of. They did the same thing in Georgian Bay (A very large bay on the East side of Lake Huron) six or so weeks ago. Here is a link to the event homepage
http://www.performanceboatclub.ca/e...46-2014-bruce-nicolle-memorial-poker-run.html
The river is part of the Trent-Severn Waterway which connects Lake Ontario to Georgian Bay/Lake Huron. There are many connected lakes in the system, with the biggest one being Lake Simcoe I believe. Just 15 minutes down the river is Rice lake.
The Trent-Severn waterway has 45 locks and it is 387 KM long