I have seen a number of floating towns in both Vietnam and Cambodia. Interestingly, the people who live in those floating towns are born there, live there, and they die there. They very rarely go on dry land and spend most of their lives floating. This reminds me of Lake Town from The Hobbit because it was a floating city as well. I am thinking of including some floating towns and cities in my fantasy book, but they will be strongholds of pirates instead of civilians.