An Israeli Inventor has developed a breathing apparatus that will allow breathing underwater without the assistance of compressed air tanks. This new invention will use the relatively small amounts of air that already exist in water to supply oxygen to both scuba divers and submarines. The invention has already captured the interest of most major diving manufacturers as well as the Israeli Navy.

link - http://www.isracast.com/Articles/Article.aspx?ID=63

article from dec 2005. Looks promising, Anyone got their hands on this yet?