http://www.digitaltrends.com/home/migal ... ate-island
The link above shows animation of architectural visions for a floating habitat.
While the focus of this particular visualization is comfortable living, the overall scope in which this item fits is an entire ecosystem based "permanently" one the ocean surface.
There are locations on the Earth's surface where weather conditions are benign all year. The Sargasso Sea is one example, in the Atlantic Ocean.
The concept of ocean living as an ecosystem is certainly not new, but the challenges of solving the many problems that will be encountered have so far kept the idea in the vision stage.
The living quarters shown in the link above need to be supplemented by agricultural facilities below the surface, and energy collection facilities around the living quarters.
Abundant energy will permit disassociation of molecules to facilitate waste processing, and eliminate the need for low energy traditional solutions.