Above, a sketch of a sea monster, and underneath, rougher tests I actually did before the sea monster, but I wanted the monster as the main image of this post, so...
The gradient map is set to 70%, so the colours faintly shine through. I think it makes a slight difference, though barely visible.
I've been playing around with gradient maps, trying to make it look like it's underwater. I want that "sunken shipwreck" feel with the black to the strong blue to the green and the yellow and white. Of course, it looks different depending on what it is, how deep it is and the quality of the water. I just want something that looks convincing.
And I'm not there yet. But it's fun and interesting to try something out when I haven't really tried it before. I knew it was there and I think I attempted something with gradient maps before, but never properly.
