Ok, you've waited long enough.

Time for an update. Travelling over oceans will now be possible. The Council of Venateri have finally developed ways to travel across the large, deep oceans, and it have caught on with the rest of the world. You can now easily travel to your allies across the world if you want. With this, it's now possible to start a Navy, if you want. Landlocked nations, your only way to start traveling is to have a city by a river, or a lake that connects to a river. You may also want to start developing dams and canals for whatever reason.

In a word....AWRIGHT!

Are there any limitations set on sea travel at the moment?

Before, it was limited to routes to nearby continents. Now, that limitation has been lift.