Featherbrain,
The way water absorbs light, you will want to learn how to use your white balance control feature. This means setting it underwater with a white reference board. Some cameras have built-in settings for Snorkel, but these are just a "standard" setting and do not account for the varying water conditions you might encounter.
I understand the urge to purchase a new camera set-up as I have been struggling with that myself for the last year (way too many posts asking which camera is better - LOL). But if you are budget conscious, I strongly suggest you look at Interceptor121's S95 set-up. The Canon S95 has a very good reputation for UW photos and his accessories are great.
Have a great day and good luck with your decision.
~Oldbear~