Sixty years ago, explorers first descended the 11,000 metres to the Challenger Deep of the Mariana Trench, the deepest known point in the ocean. In the intervening decades we have discovered more about this mysterious and peculiar environment and its inhabitants. Nicola Davis speaks to Dr Jon Copley about the race to the ocean floor and what is lurking down there in the deep.. Help support our independent journalism at theguardian.com/sciencepod