Cities above the waves

Continuing the theme of future cities, what of these jaw dropping designs for floating cities?

http://weburbanist.com/2011/06/16/the-future-is-a-beach-5-artificial-floating-island-cities/

Remember Hydropolis? Dubai's underwater hotel which is currently in limbo:

http://www.dubai.com/blog/hydropolis-a-dream-or-reality/