It sounds like something Bruce Sterling foresaw as long ago as Islands in the Net: Larry Dignan on ZDNet looks at a patent for a structure that would sit offshore like an oil rig:
Google is pondering a floating data center that could be powered and cooled by the ocean. These offshore data centers could sit 3 to 7 miles offshore and reside in about 50 to 70 meters of water.
….Now wild-cards abound. Jurisdiction issues will occur. Are states really going to allow Google or anyone else place these pontoons offshore without some tax hit?
And will Google take advantage of such a setup to bank your data like the Swiss bank money?