No further comment just hate being picky!
All of Volga (it flows into Caspian sea) and Astrakhan are in Europe.
You could even add the Karpathian Sea, but that would be kind of a stretch since it's rarely mentioned in English.
I only started really learning Geography in late August, but I'm still concerned by my lack of knowledge on the seas. That's crazy to think there are 33 of them, and that's just according to this quiz. Can't imagine how many there might be outside of this, too!
But great quiz :)