I don't quite remember the order but I do know I used multiple rounds of adjustments. (for example start with color balance, then use hue/saturation, then levels/curves, then go back to color balance or hue/saturation as needed, repeat am many times as needed)
I still didn't quite get the blue of the ocean right, I was tempted to use a selection to adjust it on it's own but I don't think that's supposed to be part of that assignment.