So this is the background for the mermaid illustration. Still a work in progress, I'd say 80% done. I spent the whole sunday painting this, customizing brushes and stuff.
I still have to put reflection on to the sea floor. Decide on the opacity a little more. I think it might be too tall and I might need to lower it. There are also some glare and colors to be added to the water, as if the mermaid were glowing a bit... but I might add them after I am done with the mermaid herself.
Part of this started as matte painting.