River rebound

When cities industrialise the rivers they were built around are first polluted, then turned into sewers and finally built over. It’s a pattern that’s repeated itself for 250 years from 18th century Paris to 21st century Manila. But across the world the fight is on to release and revive our urban rivers. They provide a cooling effect for overheated neighbourhoods, space for wildlife and a welcome place to swim or just dip your toes. Wild swimmer, rower and physicist, Helen Czerski meets the river lovers and the natural life that returns once the light is let back in.