The olympus cameras are really just water proof for some fun in the pool or maybe snorkeling, I wouldn't use one diving without a case.
I use a canon G9 with a canon underwater case to match (about a $600-$700 combo at the time).
This picture was taken at about 60-70 feet without a strobe or any flash (iso 400)
More pics here:
http://www.canreef.com/vbulletin/showthread.php?t=64839
The advantage of this camera is that it's one of the few compacts that has aperture priority mode with a max aperture of f2.8.