Looks like a great holiday and you have some great images to remember it by!
I don't want to take anything at all away from what you have already accomplished, but since you are headed to Coz soon here are a couple of things you might want to play with:
1 - change to RAW. This will allow you to white balance etc AFTER the dive - great for those reef scenes that are just too much for the internal flash. You'll be able to get some colour and better detail in those schooling fish for example. It isn't hard to shoot - works exactly the same way as jpeg...just a bigger file with more information and more room to work on at the other end. PS Elements 3 has a RAW converter...not sure which program you are using, but this would be the only reason NOT to shoot RAW (If you don't have a converter).
2 - forget the uw setting. Try manual instead. UW setting (or any of the program modes) usually does a couple of things: it opens the aperture way up giving a fuzzy or soft look to the photo and/or it slows the shutter way way down and this can give you motion blur. It works great sometimes, but in other situations it produces very disappointing shots when only a little tweak would have given a great result!
I would start, in Coz, with M mode 1/160 and f5.6. Get close and use your internal flash for light. If you are shooting with natural light, I would change your shutter to 1/100 or so...it's digital, experiment! If it's really bright out, you might need to keep it on 1/160 or even faster to get a nice blue instead of a washed out blue.
If you get a nice slow dive instead of lots of current, you can experiment with getting close to your subject and changing the aperture to f8 or so - this is great for things like small crabs, nudibranchs, urchins, sea stars and the like.
3 - shoot lots!! We want to see
