Getting Started/OpticalOcean Blog
If you're new to underwater photography, enjoy seeing uw photos and reading trip reports, you may like to read  articles in my blog:

The Optical Ocean: Above & Below

Getting Started in Underwater Photography

Underwater Shooting Tips for Digicams

5 Tips for Better UW Photos

Camera Floods: Avoiding the High Water Mark

Choosing an Underwater Strobe for Point & Shoot Cameras