"Two Men in a Tinnie" is an entertaining four-part series in which our two present day pioneers, John Doyle and Tim Flannery, unravel the secrets of Australia's greatest river system for a broad television audience. John Doyle is a city boy who's never been to the outback. His mate, Dr Tim Flannery, is one of Australia's leading scientists who knows the bush like the back of his hands. For years, they have been taking boating trips together but until now their expeditions have been confined to exploring the nooks and crannies of the Hawkesbury River aboard the Bismarck, Tim's 3-metre aluminium 'tinnie' that has only been sunk once - by John.