I usually make it up to Tobermory 3 or 4 times a year and diving can be great up there. Due to the peninsula there is very little surface water run off so the vis is pretty good most times (unless we have had a big wind in which case the lake may turn over). I've seen 80' vertical visibility and I've also seen 30'. Most of the wrecks in Tobermory can definitely claim to be wrecks - lots of rocks that brought them to their demise so they are broken up unless you are willing to go deep (Arabia, or Forest City). There is also the Niagra II which was purposly sunk which makes for a nice dive or two. Other options to break up the drive on your way up to Tobermory would be a drift dive in either the Detroit or St. Clair Rivers (I usually get 1 or 2 in per week) and my favorite dive is the wreck of the Wexford out of Grand Bend - can be a bit tricky to line up a charter to get you out to the wreck but if the weather co-operates (Late July to Mid August seems best) with a couple days of low wind and it is amazing.
Other area I'm vamilar with is Kingston/Brockville - great diving in both although no thermoclines in Brockville. Vis can be a bit more tempermental then Tobermory but water temperatures make up for it.
Cheers,
Aaron
P.s. - don't worry about the thermocline at 45 feet ... its the 2nd one at 80-90' that will have you contemplating about peeing in your drysuit
Other area I'm vamilar with is Kingston/Brockville - great diving in both although no thermoclines in Brockville. Vis can be a bit more tempermental then Tobermory but water temperatures make up for it.
Cheers,
Aaron
P.s. - don't worry about the thermocline at 45 feet ... its the 2nd one at 80-90' that will have you contemplating about peeing in your drysuit