Coast breaks new ground this week with a spectacular journey following the southern shoreline of Ireland, from Cork Harbour all the way round to Dublin Bay, as the Bafta award-winning series reaches the half-way point. In Cork, Neil Oliver explores the Titanic's last port of call and tells the tale of the Irish priest who disembarked the doomed vessel at the last minute. Father Frank Browne's iconic photographs of the ship appeared in newspapers around the world. Neil also joins the Irish Naval Service on a drugs bust as they conduct a no-holds-barred training exercise to board a suspect ship. Alice Roberts, meanwhile, tries to decipher some of the earliest writing in the British Isles as she encounters the curious carvings on one of the mysterious "Ogham Stones" - which influenced the art and science that lie behind Waterford Crystal. Elsewhere, Hermione Cockburn creates an earthquake on Killiney beach to discover how, 160 years ago, a local man, Robert Mallet, invented seismology, the study of Earth tremors that has helped save countless lives.