I only shoot RAW and I usually just set the camera WB to cloudy! seems to work best in most cases underwater. well for BLUE Pacific water that is!
then in the RAW converter I make some minor tweaks.
for the Humpback whale shots I try to actually concentrate on the whale itself and not the water color, as it was not blue in the first place! therefore that usually leads me to try to some higher temp settings.
Also, will be doing my first Caribbean dives in December, any suggestions as to settings for "Atlantic" Aquamarine water is more than welcome! Have no clue!
next couple of days I will be offline, back to Guam I go!
Chris