This hack is starting to look nice. I like that the palettes make me remember Liquid Ocean.
I'm going to disagree with Nalesnik, in my opinion, visually speaking, the worldmap still needs some work (the best part is the top island, but the rest looks messy, and the lower left island looks too straight at the bottom, reducing realism). By the way, 25 cities sounds a bit too much, unless you are really prepared to fill them with lots of ideas.
About that heroine overworld, it seems you'll follow the DP-esque style, will it be that way for all the rest of the overworlds?
Still, it's just the beginning, so there's always a lot of time for improvements. Wishing you luck on that! ;)