Winged machines are "flying" – or at least swimming – beneath the waters of the Faroe Islands in the North Atlantic.
Known as "sea dragons" or "tidal kites", they look like aircraft, but are in fact high-tech tidal turbines, generating electricity from the power of the ocean.
So, how does the technology work?
This video is from BBC Click, the BBCâs flagship technology programme.
Subscribe here: http://bit.ly/1rbfUog
For more news, analysis and features visit: www.bbc.com/news
#BBCNews