Click only the seas located within the boundaries of the European continent. If you click a sea that is not a part of Europe, the quiz will instantly end.
I tried to use only "seas", not "bays" or "gulfs". I also think it's hard, but I wanted to make it this way because most basic European bodies of water are fairly easy. If you "zoom in" to more specific seas, the quiz gets more intense. I think I'm gonna leave it. I'll fix the Greenland Sea tho.