Hey there -
We boat dive Long Point every weekend. I wouldn't recommend shore diving, because of the potential for strong currents and it would be a wicked pain to walk to with all your gear!! If you go, make sure it's early in the morning because in the summer there's a lot of boat traffic and some people don't know/care what the flag means.
It's a pretty simple dive...it's pretty much just a shelf that goes down pretty deep - we're usually in 20-50 feet, but it goes well beyond that.
There is a wreck (I think of the Flyer) - if you look directly at Long Point from the harbor you'll see a rock jetty along the beach. It's somewhere around here, and it's marked with a bouy. In low tide the wreck starts in about 20 feet and goes to about 50...high tide it's a little deeper obviously.
There are more wrecks inside the harbor, but I'd have to talk to a few people to find out where exactly they are.
Long Point is a very strange dive - like I said, Jeff and I do it pretty much every weekend, and each time it looks like we've never been there before. A little creepy but always cool.
Let me know if you want to know anything else.
Lisa