OK, so I did make it off the ship. What I found was pretty much as expected. There's another, smaller, cruise ship docked here with us, and most of their passengers seem to have left on buses too. There's a small cruise ship terminal, which looked closed up, and a coffee shop near the entrance to the container port. I'll be on deck as we leave Cartegena in a couple of hours, so maybe I can catch a glimpse of what I could have walked to.