"Eric G" ...

Which Tobermory?  Canada?  Isle of Mull in Scotland?  North Carolina?

I was up in early May and the water was 2 degrees C. So, you know that 10
weeks later it is still going to be cold. It will be much colder than
Kingston.  The deeper you go, the colder it gets BUT with shifts in the
currents the thermoclines can push near the surface around Tobermory making
it really really cold, even at 40 ft.  There are some shallow dives (like
the King) that could be above the really cold thermoclines. There is one
really nice wreck towards Manatolin that is only in 20ft of water and is
very warm at this time of year and spectacular!!! Caves are good too for
wetsuits. As far as your Zodiac goes, you've got to check in with the Park's
Dive Centre in Tobermory. You pay for a years dive pass ($15 each), show
your certs and learn the rules.  They patrol the wrecks daily, so, good
chance that you will get visited if you dive within the park (so get your
passes!).  Good to file a dive plan with the Dive Centre if you are using
your own inflatable. Your Zodiac will have to comply with all govt
regulations (bailing can, lights etc), you may need to have an operator's
licence dependent on your age and the size of the Zodiac.  There are public
launches.  They might not be happy (can't say for sure) about the two of you
diving with your boat unattended.  Good campgrounds around Tobermory, (very
cool one on Flowerpot Island that can only be reached by boat) there are
cozy but not posh hotels and motels. Food, for that far off the beaten
track, is good.  Two dive shops in town rent anything ... and they pump
Nitrox.