No open borders, um, huh?

I haven't had open borders with the Dutch for a long time, because I declared war on them since they took it upon themselves to conquer the Incas.
Now, eons later, they seem to have the power to sail through my territory without an open-borders agreement? What gives? You can see the Dutch boat in my territory right near Sana'a. And he's on the return trip; it had been parked up near the Sinai peninsula for a while, having gone through the territory I had gained from capturing Mecca.
Why can the Dutch sail through my territory and I can't get near theirs??

 

That's the Dutch Unique Power: All Dutch sea units can enter rival territory without an OB agreement.

 

And besides, all Caravels can enter rival territory!

 

Oh, so that's why the AI builds so many of them...

 

I propose that The full title of RFC be changed to: "Rhye's and Fall of Civilization - A Mod With Unique Features That You Can Read On In The Description And The Custom Civilopedia Which Too Is A Feature."

 

Seconded!!!

 

Rhye's and Fall of Civilization - A Mod With Unique Features That You Can Read On In The Description And The Custom Civilopedia Which Too Is A Feature, But Then Collapse Anyway