There is some decent diving on the north shore (of course, I think any dive is a good dive). I wouldn't travel there to dive, however, I've been to the north shore a few times for conferences at the Turtle Bay resort and any time diving is available, I take advantage. Of course, the last time was 2001, so I'm not going to be super helpful.
We found a dive shop in Waimea which had some dive maps. We did all shore dives. Shark Cove comes to mind. Decent, western pacific diving (it is what you make it).
Hope someone with more recent experience gives you some input.