You know how it is with some people? As soon as they open their mouths, you know who they are. The same is true with the whitemouth moray eel. This one is in a fairly typical position, wedged into a crevice with its bright white mouth open. They can look menacing with the head out and mouth opening and closing, but all they’re doing is pumping water over their gills, which is how they breathe.
In my attempts to identify what I see in the water, I use John P. Hoover’s book The Ultimate Guide to Hawaiian Reef Fishes, Sea Turtles, Dolphins, Whales, and Seals and his Reef Fish Hawaii – waterproof pocket guide. His website is hawaiisfishes.com.