Boats, a massive armada of every type of boat, as far as the eye can see in all directions. A mass migration of people. I get the impression that it was a seasonal thing – go to an island and harvest this one renewable resource only available there, then leave it only to return again in a year. Yet I have trouble believing that the residents of these many and varied ships were not the only remnants of humanity, a nomadic sea people.
I remember a nightclub built into one of the many unfinished floors of a massive metal ship, and from there watching a football game many floors below. I remember being hunted by an assassin, a black guy who could have been a villain from a 70s American kung fu movie. I was able to fend him off, but not kill him.