It means that I was diving in a sea that had low viz and low light levels, as if one were diving in a watery fog, and the video shows this. There was a lot of particles in the water so I refrained from using video lights as I preferred not to risk backscatter. I did some adjustments to luma in post but was content to let the video reflect the low viz low light environment.
Colour grading is a different matter entirely. If you can't see the colours with the naked eye during a dive, should one expose the missing colours in the video? If the water looks green, should one change it to blue? For wide angle with open water backdrops, I tend to lean towards leaving the water blue. With coral backdrops, I tend to introduce more red. For this video, I reduced green in many clips. Obviously my attempts at colour grading did not meet your exacting standards so I'll have to try harder for my next video.