One of the biggest challenges for an underwater photographer is choosing which lens to take. A macro setup is great for small creatures yet because of their generally longer focal lengths are fairly useless for larger species. Well, useless for photographing the "entire" subject. Using a specialized setup just means you have to be more creative with your subjects.
This Giant Hawkfish for instance was easily a good 14 inches in length and way too large for my 100mm macro lens. But as it allowed me extremely close approach, I looked for some way to creatively capture its lovely pattern and chose to focus on the converging lines around its eye. I know it doesn't show the fish in its entirety, but I quite like the intimate close up on the eye.