By accident I turned on exposure bracketing
on the G12. I heard the camera firing away after the initial shot, and I was like "what the heck?" When I reviewed the shot I was pleasantly surprised to see that a) one of the exposures was always spot on, b) since it takes a second or two to get the shot I had moved things around enough to get a different/better shot.
When I got home I went through the shots and liked the feature enough to say if you haven't used it you may want to give it a whirl. If you shot auto more than likely this feature is not available. If you have exposure bracketing on your camera, more than likely you have aperture bracketing too.
Of course you can tweak things in software after the fact, but I liked the fact that it was there waiting for me.
On a different note I feel I've used the underwater housing for the G12 enough to make some conclusions.
1) This is a bulky set up- if you want compact a G12 and a U/W housing is probably not for you (a D10 would be better)
2) The controls can take a bit to get used to
3) The results of the G12 and the U/W housing are very much water clarity dependent
4) shooting fish u/w is really difficult by yourself - I turn on macro, and continuous shooting and just fire away (I have that preset); I move fast and try to get the fish in the water asap which adds to a fast pace for shots - many are throw aways. So I play the law of large numbers and shoot a bunch quickly.
5) I need to remember to wipe the lens after a good dunking
6) shooting lefty is not easy
Knowing the above it's still a great setup for above/below water shots. The catch is you have to live with the bulkiness.
Some samples of a recent outing below (I liked the first and last one):