I came close to buying an Olympus. The picture quality looks good and the form factor is good. The thing that turned me off is the responsiveness (lack of). I only tested in the store and read reviews so take it for what it's worth, it just seemed like it took so long to power up and focus and such. I value quickness more than anything in a fishing camera.
The Canon waterproof stuff is not typically sold in big box stores. You can get it on Amazon or probably at some specialty shops more focused on cameras.
I've had 2 lines of Canons
1. A regular P&S with the waterproof case, Canon makes a snorkeling case to fit all of it's cameras. It's clear plastic, lets you do all controls from the outside, the pictures came out great. The negatives are that the case itself is like an extra $100, and it takes your thin little P&S and turns it into the size of an SLR.
2. Canon Powershot D10 - this is what I have now. It takes excellent pictures, the camera review sites rate it a little above the Olympus's. It is ridiculously quick to power up and focus, I can power it up, focus, take a picture, and shut it off within 5 seconds. Drawbacks are that it's a little more money than the competition, and it has this weird egg shape. It's not huge, but it doesn't fit in a pocket right.
They've just come out with the Canon D20. I have not seen one. Looks like it's a bit more money, and the biggest upgrade is with video and a bigger screen, and a skinnier frame. Also a little wider angle lens. All else being equal you'd have to decide if that's worth the money. My concern would be to check what they sacrificed? Lens speed, sensor size, aperture, shutter speed? They addressed where the D10 fell short of it's competition, but I'd fear they may have sacrificed what it excelled in to do it. If they made it just like everything else on the market that'd be a step back IMO.
