I was playing an archipeligo map, with high sea levels, and tiny islands (probably about the only conditions where this would be noticed or make a difference). And in it, when I went exploring, I discovered that a couple of other civilizations had set up colonies in islands that I couldn't reach along the coast.
At first I thought that there was simply a really long path that they had taken to get there, but I had built a few caravels and sent them to search out these islands. I found that there was no possible way to reach them by following the coast, any way to reach them was cut off by a square of ocean, and pathfinding confirmed that there was no path by which they could be reached by my own galleys.
Then I noticed a galley in that area from another civilization carrying a settler, so I watched it, and it moved up to the area between two islands, where the coast was nearly touching, with one ocean square between, (coast-ocean-coast). On one turn it was on the coast on one side, on the next it had moved to the coast on the other side, without noticing that such a move should have been impossible, and wasn't possible for me to do, due to the ocean square between.
At first I thought that there was simply a really long path that they had taken to get there, but I had built a few caravels and sent them to search out these islands. I found that there was no possible way to reach them by following the coast, any way to reach them was cut off by a square of ocean, and pathfinding confirmed that there was no path by which they could be reached by my own galleys.
Then I noticed a galley in that area from another civilization carrying a settler, so I watched it, and it moved up to the area between two islands, where the coast was nearly touching, with one ocean square between, (coast-ocean-coast). On one turn it was on the coast on one side, on the next it had moved to the coast on the other side, without noticing that such a move should have been impossible, and wasn't possible for me to do, due to the ocean square between.
