Turtle pinnacle's actually seeing less dive traffic these days, in year's past there were two to three large operators that went there several times a week so it had a lot of word of mouth, and wouldn't make my top list but it's still a good dive though, been seeing fewer turtles the last year or so. Gerard's list is spot on, I'd add Pyramid Pinnacle/Pine Trees Pinnacle/Harlequin (probably another name or two for that site out there too). Kaiwi Point/Pawai Bay can be awesome to OK/good depending on the day. I frankly like sharkfin rock a lot too, as long as you're following a good guide. There's some great one way dives that can be done if conditions are right. Kona has very few if any mediocre dive sites, I can only think of two that I avoid and going through my GPS we'd been to over 50 moorings and anchor spots over the course of the spring and summer... the dive ops here are going to try to give you the best diving they can depending on the conditions of the day and who's on the boat so don't get too hung up on having to see specific sites.... it's all good.
