Any Great Dive Sites for Hawaii?

I'm taking my family to Hawaii in early April to dive and lay around. We'll be on the Kona coast of the big island (Hawaii). We've signed up for dives with Dive Makai and plan to do 2 Manta dives.

Are there any sites near there that you think we should be sure and dive?

Thank you for your help

Regards,
Bob

I have only been diving in Maui, but I was not impressed due to a lack of soft corals, invertebrates, etc.

But if you can run into mantas, that would be awesome...