How do I establish a sea route?

[MyOlde]

I'm on one continent, the Chinese on another. I have at least one harbour on my continent and I've managed to plunk a little village down on the Chinese continent and built a harbour there. I have installed roads that connect to the Chinese roads which, I can see quite plainly, lead to their capital, Beijing.

I am swimming in luxuries and want to trade with them but I get the message "Until we establish a sea route, we cannot trade." What more do I have to do?

I am limited to galleys at this point which sink most of the time trying to make the trans-oceanic journey.

Thanks for your advice.

[DrFell]

You need astronomy and navigation to establish routes across sea squares, I believe.

[MyOlde]

Ahh, thank you, Dr. I for one love thee.

[DrFell]

You might just need astronomy so check it out when you get that.

[Harovan]

There must be harbors in both cities. The route must not go through the territory of a civ you are in war with.

- If the route goes over coastal tiles, but not sea or ocean, you need Map Making.

- If the route goes over at least one sea tile, but not ocean, you need Astronomy or need to have built the Great Lighthouse.

- If the route goes over at least ocean tile, you need either Navigation or Magnetism.