Newbie - managed to fix colour balance before but seem to have forgotten how!

[spookie]

Hi everyone!

I am a complete newbie, I only downloaded GIMP a couple of days ago. I have a few underwater photos I'd like to improve the colours in - as far as I understand it's mainly colour balance and white balance I need to alter. So I had a play around, and was pretty happy with what I managed to do! HOWEVER, I have obviously misremembered what I actually did, as tonight I couldn't seem to have much success on my other photos, so I went back to this one and tried to recreate what I did... and I just cannot seem to get it close!

I would be incredibly grateful if anyone could help!  I really thought I just tried adjusting color curves (perhaps after using auto fix white balance), perhaps with slight changes of hue/saturation. But no matter which channels and combinations of channels I try adjusting now, I can't seem to get the result I did the other day...

So, how would you lovely people get the first image to look like the second? (Or, if you can make the second one better please do tell me what I should do!)


Above: 1) The original image (smaller)



Above: 2) The result of my first editing attempts, that I'm pretty happy with   




Above: 3) One of my many attempts to repeat the edit, and failing - I either seem to just change the overall colour, or by getting either the sand, shark, or sea closer to the correct colour it seems to make the others worse, I must be missing something...

Thanks very much in advance!

Mel