Color editing underwater video

A year of two ago, I was in Mexico, snorkelling, using an action cam, cheap, sub £/$ 100 excellent for the price.

Color was a bit off due to (some) loss of RED, I managed to find a help video on Youttube that explained how to fix. I was happy with the results. (Lost the video link now)

A couple of weeks ago I was in the Atalntic at 30m / 101 ft in a submarine.

I took some Video (Canon EOS 5D MKIV) as expected LOTS of BLUE cast.

Can anyone point me to some help as to improving the colors?

Video sample attached. I have a lot to do, no luck making any look ok.

Some are a very much deeper blue,

The sand should be sand colored, the fish are silver and black.

Any suggestions would be gratefully received.

Thanks in advance.