When listener Watum heard about the Titan submersible implosion in the news in 2023, a question popped up in his mind: if a machine that we specifically built for this purpose cannot sustain the water pressure of the deep ocean, how do fish survive down there? In this episode, we travel with marine biologist Alan Jamieson to the second deepest place in our oceans: the Tonga trench. Meanwhile, presenter Caroline Steel speaks to Edie Widder about the creatures that illuminate our oceans, and travels to Copenhagen to take a closer look one of the strangest deep sea creatures and its deep sea adaptations. But even fish have their limits! Scientist Paul Yancey correctly predicted the deepest point that fish can live, and it all comes down to one particular molecule. So is there anything living beyond these depths? Well, there is only one way to find out… Contributors: Prof Alan Jamieson, University of Western Australia Luke Siebermaier, Submersible Team Leader, Inkfish Dr Edie Widder, Ocean Research & Conservation Association Peter Rask Møller, Natural History Museum of Denmark Prof Paul Yancey, Whitman College Presenter: Caroline Steel Producer: Florian Bohr Editor: Martin Smith & Cathy Edwards Production Co-ordinator: Ishmael Soriano Studio Manager: Steve Greenwood (Image: Deep-sea fish - stock photo, Credit: superjoseph via Getty Images)