A norweigian energy company, Norsk Hydro, has developed a windmill, "Hywind", to be placed into the ocean. It will rice 80 meters above the water, that's roughly 262 feet for you ISO-handicapped people ;), and will be 120 meters submerged.What an excellent idea! Think about it. Who cares the the deep ocean looks like? But people do care what their beach lines looks like.
Welcome to the future!
http://www.hydro.com/en/Press-room/News/Archive/2007/06/Technology-cooperation-on-full-scale-floating-wind-turbines/
Update 18.6.2016
The prototype has been working great in Norway. Now they are setting up a farm in Scotland