Apologies for missing the various replies.
Again, if you want to see good numbers of corals at Hanauma Bay, you can see a few in the inner reef lagoon, at the very edges. The "back channel" has a number of good massive encrusting corals, as well as Oahu's biggest coral on the way. (mostly Porites lobata, P. lutea, a few P. compressa and Montipora capitata). The "keyhole lagoon" also has a few Porites lobata or lutea and M. capitatas).
But to really see the coral, you have to go through the channels. This can be very dangerous, please check with the lifeguards, have a buddy, and take proper precautions. To include not going if you're uncomfortable with the waves. (as I am about half the time I go. Go as early as possible and listen for the sea states). And even then, the time's I've gone it's not been a pleasant swim.
But the SPS growth is great. Unfortunatley, it's mostly the same species because the coral diversity in Hawaii was never very good in the first place. (e.g. Acroporas were thought to be myths in the lower islands, until someone found 1-2 colonies in the past few years)
https://www.youtube.com/watch?v=jbs-...index=99&t=69s
And again, I would say the right parts of Kaneohe or Lanikai Beach are better and more reliable easy beach swims to see corals.