This is very dramatic! The perspective makes this so overwhelming, in a good way! XD I would only suggest adding more darker tones in the water to tie in with the background. The person in the white cloak is also kind of hard to see. Depending on how hard he light coming Olkin, you could probably make them a little darker to see them better. :3
Wow, this is absolutely gorgeous, this definitely gives me that cool feeling, which I think is conveyed here pretty well!
For the sky, I agree with ~mad-hat-ink, I believe more stars would compliment this very nicely. As for the water, maybe blend them in as they go outwards? That is somewhat confusing to word, but I think if it were blend more while going out it would look a lot more like water ripples. I kind of phrased that really badly, if you need a better explanation I can offer one.
Otherwise, this is a very stunning concept drawing! The composition is wonderful, the concept is unique and it is amazing how eye-catching this is.
Very beautiful. It would benefit from more stars, I think. And like you said, more water detailing...I think my only specific suggestion on that would be to make the change in line direction more gradual. Does that make sense? Like, graduate the ripples more slowly, a little bit more than you have done here. I love the circular thing you have going on here. Really pretty artwork!