Pytheas of Massalia (Marseille), mariner, explorer, geographer and astronomer, made a pioneering voyage into the then unknown Atlantic around 325 BC, reaching Britain and the Baltic; this book collects and translates the references to him and his book (which is lost), and discusses and explains them. The Greeks of Pytheas' time knew virtually nothing of northern Europe beyond the often-fantastical stories of traders, and Pytheas was the first person to provide factual, first-hand information on this region. His journey covered Iberia, France, Britain, from where he travelled so far north that he encountered ice floes; he then reached the Baltic. It was he who recorded Thule, and his astronomy enabled him to locate it on the Arctic Circle. Two thirds of our references to Pytheas come from Pliny and Strabo; their methods of work, as well as the perils of manuscript transmission, are explored in this volume. Scott also includes discussions and appendices on these areas to enable the scope of available references to be understood as a whole. There are some details of Pytheas' voyage that are lost, but the book offers balanced reasons for proposing how we may reasonably fill them in. The breadth of Pytheas' achievements and the areas and topics his work covers mean that he has a wide range of appeal within classical studies and ancient history. This volume provides an invaluable resource to undergraduate and postgraduate students of early geography and astronomy, and Greece’s knowledge of and relationship to the rest of Europe in this period.