The site won't work for me, either. I saw the image on Subsim's main page. I am always amazed at how sunken ships on the Great Lakes stay so well preserved. Gotta love that fresh water!
Anyway, I'm not sure I would call this find the "Holy Grail". I think "Holy Grail" status would probably lay with this ship...
http://en.wikipedia.org/wiki/Le_Griffon