Aloha FoShezzie.
Lets get started on the happy foot. Spearfishing in Hawaii is a delicate subject. You have the right idea if you plan to eat what you hunt, and only take what you need, IE the minimum that you need. Outsider or not, you most likely won't be looked upon favorably if you have a spear in your hand. And do not EVER have a spear and scuba gear at the same time. It might not be illegal, but I wouldn't do it. Remember too that a dive shop, or better yet a free diving shop, might be more expensive but they will also have helpful info for you. Such as where to go and where not to go, both for good fishing, safe water, and to avoid trouble. Also I recommend getting the book put out by the Division of Aquatic Resources (DAR) on locations and animals and areas that are protected, regulated, prohibited, toxic, etc. You can contact DAR directly for the book or a QUALITY retail location will have that for you, and they are free. Most locals are friendly if you follow the pecking order, same as surfing. One last note, the only people who make comments about the Tiger Sharks are the ones who have not had a real encounter. Sharks in Hawaii are sacred, and their discussion in many forums is taboo, so exercise caution. One last note for your own enjoyment, hunt during the week when most everyone is at work. You'll have the place to yourself and you'll be much less likely to get hassled. All that being said, I'd rather see you buy a camera than a spear, but the reality is that one bottle of sun tan lotion or bottle of hair conditioner kills more marine life than a single spear.
Matthew
Hey Wildcard, can you tell my medication is kicking in full power? This has got to be the least confrontational I have ever been.