There is no torch. In "cave" there is a wide opening behind the camera, this is how I get there. Also since light falls off with distance it looks like the camera emits some light.
I have an idea to try: when clipping is applied to colored highlight, the highlight remains colored (6-axis), or saturates slowly per rgb channel (levels). It might be more convenient if clipping/overflow resulted in desaturation of highlight.
GOPR0233
Hard to say, some bright spots could be dead coral, I consider these white. Also coral rock to the right.
Ideally we want white references at multiple distances. The fishes on top maybe gray or very close to.