Separating the bulk of the Australian population and the inland is the Great Dividing Range. It may not be spectacularly high but at 3,500km it is the fourth longest mountain range in the world. Rising in the Casterton Plateau in Western Victoria, the Great Dividing Range stretches up the East Coast, ending at Mt Cornwallis on Dauan Island, just seven kilometres from PNG. In the tradition of Two Men in a Tinnie and Two in the Top End, satirist John Doyle and environmentalist Tim Flannery travel along the Divide by car, by foot, by boat and by air, as they endeavour to climb six of the most important spectacular peaks along the range.