Hope that subtitle doesn't attract the wrong sort of people!
Having a flash on your camera gives you a number of options beyond shooting available light which I discussed earlier in the blogs about Custom White Balance and shooting RAW.
Taking pictures and video while diving has become increasingly popular since the advent of digital cameras. But the camera market has also become more and more complex with numerous pitfalls for would be underwater photographers. In this series of blogs I'm going to try to clarify some of the factors that make some cameras better for underwater photography than others.