[quote=Pathfinder]
As a whole I think its fine, but it seems that the Vodyanoi seem more at home close to shore than deep oceans with their legs instead of tails. However I do find them interesting. Take note that if their biggest cities are in the deepest parts of the ocean than they would have to be ravaged by both the Kraken and the Lord of the Deep's minions.
[/quote]

A good point. And I did want them to be froglike & amphibious to an extent. Close to the shore makes more sense. 

Let's say their cities are close to the shore but very well hidden within underwater caves and such. But in ancient times their cities were in the deep. At one point they were cursed with the inability to bare offspring on their own and with monstrous threats taking shape in the deep, they were forced to flee to higher waters. 

Perhaps then over time they evolved into their current form.