This will be a tough job!
Water absorbes colour; that's why everything turnes blue the deeper you go. This way you will be left with just only blue and when there is no other colour in your image you cannot apply a change in saturation to bring these colour up.
The only way to avoid this problem is to use flash light. But this way you will encounter other problems like small particles that will lighten up in your image.
My 2 euro cents. :smile: