Derek Brockway visits Rhondda Cynon Taf for a seven-mile circular trail that starts and ends in Hirwaun. On his route, he learns about the area's industrial past, visits a whisky distillery and takes a ride on the world's fastest seated zipline. Meanwhile, wildlife expert Lizzie Daly investigates how otters are under threat and Onkar Singh Purewal goes on a trek with alpacas across the Brecon Beacons