For equipment, I use a digital camera: Olympus C40z with an underwater housing: Olympus PT-012.
I can't afford a strobe yet, so only using the internal flash.
I guess underwater photography is a little difficult in that several factors affect the ability to capture nice shots:
- your buoyancy control
- you can't use a 400mm to capture shots of animals like in wildlife hence, stealth techniques play a part. Me, I'm just plain lucky
- without a strobe, I'm pretty much limited to macros. The eel shot was taken about 10-15cm away. Just hope it doesn't think my camera is food.
If your question refers to the settings, you can check the exif information on the picture. It's still intact.
Anyway, I purely an amateur. Don't take my words seriously.