You can also go the cheap route and but a soft underwater case.
This one (DICAPAC WP-410) fits your camera.
$39.99 CDN
here
It may not be quite the same as a dedicated underwater camera but I bought one before our trip to the Bahamas last fall and it worked fine for what we needed (snorkeling, swimming, sand, cruise ship's pool). Absolutely no water or sand got near our camera, the case worked great.