Extreme Engineering - Season 2 Episode 5 : Iceland Tunnels 2011

Around 200 miles northeast of the capital, Reykjavik, engineers are hard at work drilling 72km of tunnels deep in the mountains. Three full-face boring machines have been specially shipped from the US to this remote site, 100 miles south of the Arctic Circle. The tunnel’s purpose is to guide water to the valley floor from reservoirs that are also currently under construction. The cascading water will drive six turbines, each with a rated output of 115 megawatts. With a total capacity of 690 megawatts, it will be the biggest hydropower plant in Europe.