"Maybe take a look at Franco's dive map. "
That might get me in the general area, but I wouldn't trust even an afternoon expedition on any triangulation based on hand-drawn coordinates on a tourists' map. I doubt it would be accurate enough, for example, to find the buoy of the YO although admittedly, I've never tried.
"Could it be the same as the site in Kaaawa before you get to Crouching Lion? That is a scary dive. Ripping currents and about 2 foot viz with massive turtles and hammerheads. I've never been so spooked. I can direct you to that. Some small ship wrecks in there and lots of pukas."
No, Kahuna Canyon is supposed to be offshore of Mokuleia just west of Haleiwa, but I would be very interested in the site you're talking about. I've been all around there and have found a bunch of rare fish but have never seen the hammerheads. Could you PM me a few details?