Polar explorer Paul Rose heads for the North Pennines in the latest stage of his journey along the Pennine Way. As the route celebrates its 50th anniversary, he goes white-water rafting down the River Tees - and takes in one of Britain's best views at High Cup Nick. Paul also hears about a weather phenomenon unique to the Pennine Way, and spends a night at a remote mountain refuge close to the highest point of the Pennine Way.