Down deeper where it was almost black I had to use a flash, which restored a lot of the color, but also created back scatter. Reducing back scatter really requires using an external strobe flash, like the one I added to my birthday list :). But the flash did restore a normal color profile. One of the activities during our deep dive was to write on a waterproof tablet what color we thought many colors were. Most looked gray or white, when in fact they were all the colors of the rainbow.