Ok, here's a question from a non-digital camera person BUT a person who has and does white balance broadcast video cameras for TV production. How can you correct a color if you do not know what the color is??? If you took a picture at the start of the dive of a white card, at depth, then you have a VALID reference point to correct the colors, otherwise you are guessing, right?
The purpose of white balancing a camera is to "define" white for the electronics in the camera. In fact, we MUST do both a white and black balance before a camera should be used.