If you are into spear fishing, I just went with a guide on the big island a week ago and it was awesome but I've gone spear fishing 4 times before. It takes a pretty specific skill set and has kind of a steep learning curve, for the obvious reasons of: the swimming/snorkeling with waves, diving with a wetsuit and weight belt, ear equalization, holding your breath, the spear gun, and not being scared of sharks lol. But it is a blast, especially in Hawaii with the water clarity and abundance of fish. I got a 12 lb Omilu (bluefin travalley) and a nice Roi(Peacock Grouper) at close to 40 feet deep along with other easier to come by catches. We even got a chinese place to cook up the Omilu for us that night, yum.