A brilliant proposal has been made to build a massive 2,400 MW seawater hydro project using the Mediterranean Sea, and the Dead Sea, which is below sea level. The Dead Sea Power Project would use the ocean to make hydropower, in a world first.
http://www.greenprophet.com/2012/01/first-sea-water-pumped-hydro-proposed-staggering-2400-mw-potential/