Antarctica is a 'natural reserve, devoted to peace and science' - that’s according to an international treaty. But with visitor numbers at a record high, how does tourism fit into that – and what kind of impact is it having on its fragile ecosystem? We discuss whether tourists – and even scientists – should be allowed to go at all. Swimming in the Seine has been banned for more than a century because of pollution concerns. The main culprit? Human waste. We find out if it really will be safe in time. And every summer we ready ourselves for 'flying ant day' – that one day where winged ants take to the skies across Britain. Or do they? Presenter: Victoria Gill Producers: Sophie Ormiston, Ella Hubber and Gerry Holt Editor: Martin Smith Production Co-ordinator: Jana Bennett-Holesworth