I've just come back from the Red Sea and took my camera along on most of my dives. I do have an external strobe, but for most of the shots the light was so strong that the camera didn't fire it. The result is that I've got lots of shots with a strong blue cast.
I can always just play with the hue/saturation in Photoshop, but it occurred to me that a quicker method might be to stick a red layer over the top of the images. It seems to me to be essentially the same as the red filters that are often supplied with housings. Has anyone ever tried this and what were the results like?