Steve Backshall takes us to a place few have ever visited - the deep sea. 99 per cent of the space on Earth inhabited by life is under the ocean and almost 90 per cent of this is deeper than a kilometer, a place of perpetual darkness and crushing pressure. Far from being lifeless, the vast inner space of our planet contains an extraordinary array of beautiful and bizarre creatures, from 40m-long jellyfish to grotesque angler fish and vampire squid. Our journey from the sunlit surface waters to the deepest reaches of the abyss reveals how life persists in such a hostile world. A BBC Production.

Originally released by BBC Worldwide Learning, 2012. Streaming video file encoded with permission for digital streaming by Infobase on October 03, 2015.