Called the Swimming Cities of Serenissima, the boats looked like something out of the 1990s post-apocalyptic movies âTank Girlâ and âWaterworldâ sprinkled with a bit of swamp water. Not only the craft themselves was made from re-used material, (including modified Mercedes car engines), but the team also picked up more flotsam and jetsam on their crossing, which they installed in a »cabinet of wonders«.