Toby is a great place to dive with lots and lots of wrecks, some right off shore. We love to go there because the visibility is great for the Great Lakes. if you want to look at some Pictures of some of the wrecks hit the www button to be taken to my website, I have the Alice.G tug, Caroline Rose, Sweepstake, Wetmore wrecks listed with some pictures so you can get a rough Idea.
If you're diving with a wet suit, you might want to go a little later on in the year, ( end of July August), water can be cooold in June.
As far as dive operators I have never heard any complaints. The tiny little town sits right on Tobermory harbour so you can walk from dive shop to dive shop within a minute or two.