I found some very interesting lagoons and such areas when i was in Hawaii. Some of the most interesting places are inland. Some landlocked lagoons etc, but not that many marine fish, although some of the lagoons are interesting with regards to fish. Unfortunately for less crowded that does mean further from the ocean. I was not very into fish when i was in Hawaii either, while i was but i was very afraid of the water...couldn't swim then
I relied on glass bottom boats mostly.