I will say, you don't need a "big and expensive" camera to get great underwater photos. It helps to have additional functions, but there are a couple major items that make it possible, everything else is refinement.
1. Waterproof housing
2. Need LOTS of light. External strobes really are necessary and arms to get them away from the lens.
3. Shoot "up", not "down". Capture as much natural light as possible.
4. If you want color in your photo, need to be CLOSE! General rule of thumb, no further than arms length away (2-3ft).
Follow these simple rules and you can capture some amazing photos too.
