I lived in Grosse Ile, MI for a number of years. Prior to 9/11, you could boat over to Windsor, Boblo Island or Amherstburg and just call a Canadian Customs from a pay phone to get an authorization number to be in Canada. That was it!
After 9/11, you had a bunch more hoops to jump through but you still don’t have to declare arrival until you have touched ground. If Canadian Coast Guard picks you up then I would imagine “no harm no foul”.
Canada is practically the 51st (58th) state.
Having grown up in Ottawa and having spent a lot of time in the Thousand Islands. I recall that when I was in my early twenties, you could go Boldt Castle on Heart Island, and walk around the property.
Eleven years ago, I was showing my old stomping grounds to my new Alberta wife, who had not been East of Regina. We took a Thousand Islands boat cruise, which landed on Heart Island. I was very surprised that they now had a Customs checkpoint on the island. Luckily for me, at that time, only a Canadian driver’s license and birth certificate were required. Now, a Passport is required for a Canadian to travel into the US, even a 2 hour visit to a tiny island in the middle of the St. Lawrence. And all this because of muhamedan lovers like BJ Clinton, G. W. Boosh and 0.00. How depressing!
My Grandfather grew up in Sombra, Ontario, across from Marine City , MI. There is a ferry boat crossing there with a small 1-2 man customs station. The last time I rolled through, maybe 12 years ago, I remember the customs guy leaning on a wall, kindly talking with a lady in her car. A local walks off the ferry boat with a “Mornin Joe” and heads past on his way to work or whatever.
I’m sure it’s much different now.