Other Civ's Ships Invade My Borders?

[siouxfallsciv]

Suddenly I look north towards my city on the coast and there is an English ship sitting next to it. A few turns later a Spanish ship, then a Japanese ship, then a German ship, whats up with this "ship"

Am I the only one experiencing the enemy ship problem? Keep in mind I wasn't at war with, or had open borders with any other Civ whose ship crossed my borders. Don't ships respect borders too? Can any one explain or has anyone had this problem also?

 

[Tarascan_King]

If its a caravel it can enter your borders without a open borders agreement.

 

[siouxfallsciv]

I think it was...thank you!