We know so little about the depths of our oceans that they might as well exist on another planet. The majority of the sea floor has never been visited by humans. As to what lives and feeds and breeds down there in the icy depths, it remains best left to our imagination.  Sylvia Earle, an Explorer in Residence at National Geographic, has been exploring the sea since she was a teenager, and she has been diving since the 1950s. In those early days, as she explored the shallow seas in scuba gear, she was frustrated at not being able to see what was going on in deeper waters. “From the earliest time I had frustration, to go out to the edge of a drop-off, as deep as I could go, and look over, and the fish didn’t stop, the ocean didn’t stop. I wanted to go over the edge and see what was in the deep water beyond.  “Technology was the key for me to be able to see the ocean with new eyes.”  Earle founded the company Deep Ocean Exploration and Research in order to investigate this world, invisible from the ocean surface. One of the submersibles the company is currently designing is what Earle calls her “dream machine”; a submarine that can take scientists all the way to the bottom of the deepest ocean floor, 11,000 metres (33,000ft) underneath the ocean’s surface.  Watch and read more from our series The Genius Behind: the most amazing and sometimes little-known technological and scientific breakthroughs of modern times, and the innovative minds behind them.  If you would like to comment on this, or anything else you have seen on Future, head over to our Facebook or Google+ page, or message us on Twitter.
Ahead of a new series of Genius Behind – stories from the world’s most innovative minds – BBC Future revisits ocean explorer Sylvia Earle’s quest to the deepest parts of the oceans.