The team travel from Berwick-upon-Tweed to Aberdeen, highlighting Edinburgh's close connection with the coast. Miranda Krestovnikoff dives into a spectacular marine reserve off St Abbs, Alice Roberts discovers how the Forth Road Bridge is threatened by rust, and Neil Oliver recreates a desperate wartime scheme to train seagulls to search for German U-Boats. Mark Horton discovers the secrets of the sailing boats that could outpace steam, and Hermione Cockburn explores the extraordinary 400-year-old connection between a picturesque coastal village and the birth of deep coal mining in Britain.