The Islander is a wreck, shore dive, immediately behind River Hospital in A Bay. There's a little park set up for divers behind the hospital, with a gazebo and nice entry ramp, plus parking. Go straight out, about 50', you'll see the dive flag tie-off on the wreck at about 27' depth.
For a dive two, head right (East), follow the contour at 25 - 30', you'll see buoyancy hoops, a platform, then a bit past that a big chain headed down from above water level -- follow that and you'll get to a big concrete block with a manmade attraction just to the east of it. Come up to about 40 feet, continue east and you'll see a cool overhanging rock, with a second one about 50' past the first. Come back up to around 25 - 30', follow the contour back to the entry point.
TIDE and Hunts in Clayton (30 minutes away, US) run charters, as does Pleasure Divers out of Rockport and Brockville (15 - 30 minutes drive East after crossing the 1000 Islands bridge into Canada). Otherwise, head to the Ogdensburg bridge crossing, go over, and there's the Connie, the Rothesay, and a scuba park, all in the immediate vicinity.
(Don't forget your passport if you want to do the Canada dives...)