Ikelite housing for HF100 - seems very well made, reliable, very positive closure. Fiddly controls however, don't expect to be using the joystick toggle button much at all. You can see the lcd screen just enough when it is held half-open to frame shots, I had no probs with that.
Raynox 5050 HD - Necessary for U/W since it means you can get close to subjects and reduce the haze, get clearer picture and better colours. On surface tests, it causes a very soft picture at full zoom, but it's cheap don't expect canon pro quality glass.
Ikelite flat expansion port for Raynox 5050 - Well made again, fits firmly and positively in place of the regular flat port. Unlike the dome port, you sacrifice a little bit of wide angle ability due to refraction (?) but the flat port allows the camera to macro focus and get great shots of tiny bitty things which is important where I dive.
I do get a tiny bit of vingette as you'll see in this video, if the embed works (edit: it doesn't, please follow external link)
big rocky
This dive site is nothing special, in fact it was just recon to see if this shore dive very close to where I live was any good, there were a few things to see but it was more just about getting wet and testing the camera. I hope to get some quality time at our really great dive sites in the next weeks.
If you have any questions, just ask! I had a terrible time getting information about the combo I wanted to use but feel I finally did all the necessary research so I'm happy to share.