You see lots of cool critters normally reserved for aquariums.
Walking by the pier in Waikiki we saw this:
All taken above water, from about 5 feet above the surface of the water:
It seems that the Yellow Tangs and Sgt. Majors were the only ones not too shy for photos:
There is a Humuhumunukunukuapua'a in here:
Some more urchins:
And Crabs!