Loss of color under water
The camera doesn't know that you are under water. So the camera doesn't correct for the color loss automatically. That is the reason why cameras have a special option for under water. Because the loss of color is dependent of the depth such an option works best at the depth the vendor of the camera has decided on. And that is exactly the reason why I am not happy with such a custom option.
Luckily lots of cameras have an option to set the color balance manually. The Sealife DC500 has such an option and I have used this option to take a second picture of the same soft coral as in the first picture.
This time I was more careful to push the trigger button. As a consequence this picture is sharp. Apparently there was a bit more light available because the exposure time is now 1/52 sec.
All the other settings are the same.
Setting the color balance manually is done by pointing the camera at a pre-determined color (white of gray) and then pushing a button. In this way the camera is told which color should be white or gray. If your camera has an LCD-panel the image will show too much red because your brain still corrects although you camera already made a correction. As you can see this picture is already much better. The green is gone and the picture has a more natural color although the picture as a whole still lacks contrast.
In my experience setting a custom white balance gives acceptable results till about 15 meters in clear water. From 10 to 15 meters more and more correction is necessary in the post-processing. At depths of 15 meter and more there is so little color that it is almost impossible to correct this in the post-processing. Keep this in mind for your next dive. Stay shallow; then you will have more available light and more color.