Don't buy this underwater case!!!! It's a lottery. If you're lucky you might buy four or forty underwater cases from Canon and have no problems. Me I got one for a G10 and no probs but the first time I went down with my S90 I got a leak. I firstly thought this could be my mistake, but nope: I took it down again without the camera a couple times and got the same result: water inside.
Do you want to save a little few bucks buying the Canon underwater case instead of Ikelite? Go ahead! But remember Canon doesn't give you a proper (if any) warranty on underwater products, so it might as well happen to you what happened to me: money out the window for the case, money out the window for the liveaboard trip that was intended as a photography liveaboard trip, plus money out the window for my S90 that died shortly after the warranty expired due to water damage. Thanks Canon!!!!