toller pretzl said:I see the AI sailing on the ocean in caravels, when they have not yet discovered Astronomy. How do they do it ? I know from the F4 screen that they don't have Astronomy. And the Civilopedia tells me that it's Astronomy that enables on the ocean.
Caravels and galleons always have the ability to cross ocean squares.
Astronomy allows you to make trade connections and trade routes across ocean. The trade routes don't affect and aren't affected by how your units can move. Trade routes are set up automatically and out of your control. Trade connections across oceans also means you can trade resources to civs across the ocean.