When OceanGate's Titan submersible went missing last June, it sparked a monumental rescue mission which captured the attention of the world. After days of searching, authorities concluded that the vessel had suffered a catastrophic implosion, and that all five passengers died almost instantly. For the past two weeks, the US Coast Guard has been hearing testimonies from former employees and industry experts, to try to identify what went wrong. On this episode, Azadeh Moshiri is joined by the BBC's science editor, Rebecca Morelle, to discuss the most revealing evidence, and consider whether the tragic event could have been avoided. Producers: Laurie Kalus and Eleanor Sly Sound engineers: Phil Bull and Mike Regaard Assistant editor: Sergi Forcada Freixas Senior news editor: Richard Fenton-Smith