Cities on the sea? I would argue that we still have plenty of land to settle before this would ever be necessary. Afraid of rising sea levels? A well built wall will probably do. Despite that, it's still interesting to imagine what form sea cities could potentially take. Check it out on MSN.

http://innovation.uk.msn.com/tomorrow/the-amazing-new-cities-on-the-sea

...and your reward for taking the time to read this post is this awesome gif of a unicycle rider eating it.

enjoy.

http://imgur.com/gallery/YqkLVSc