I would highly recommend SNUBA. I've been a snorkeler for a long time, but never SCUBA, nor am I certified for SCUBA. We did a SNUBA trip while we were in Hawaii last month and it was absolutely amazing! Instead of carrying oxygen tank in a typical SCUBA dive, the oxygen tanks are placed on a floating raft. Then there's a 26ft long tube which connects the oxygen tank to you, so you are underwater and can breath from your month. The device that you bite on for SNUBA in your month to breath is virtually the same as what you use for snorkeling. Having oxygen underwater made a huge difference and SNUBA was just great! SNUBA also works if you have children who otherwise can't SCUBA. However, we did this while we went to Maui though, so I can't recommend one from Aulani. But I'm very sure you can find one in Oahu.