Investigations off the coast of Scotland reveal one of the greatest acts of defiance in wartime history, dating all the way back to World War I
The discovery of three German U-boat wrecks, including the world's first ever stealth sub, reveal dramatic stories of 20th-century conflicts at sea.
The tragedy of the Empress of Ireland, Canada's 'Titanic'; and El Faro, which was caught up in a tropical storm in 2015. Both wrecks show how quickly danger can rise up at sea.