Narrated by David Attenborough - the first episode of this stunning new series reveals the hardships and hazards involved when filming wildlife in the world's most extreme environments - the Arctic and Antarctic. Legendary polar cameraman and diver Doug Allan relives some of his most hair-raising encounters and returns to the place where his underwater career began - the freezing depths of a Highland river.

Filming the wildlife in our skies stretches the skills of any wildlife cameraman. Birds move in three dimensions and constantly change direction so keeping them in the frame and in focus is challenging. In the third episode of this illuminating series, Scots-based cameramen John Aitchison and close friend Mark Smith reveal some of the more unlikely corners of the world where they have filmed birdlife, from a rubbish dump in Dehli to a motorway flyover near Birmingham. The results are mesmerising.