Rewind to 1858, and the Thames was a literal health hazard. The "Great Stink" forced Parliament to soak curtains in bleach just to function, and typhoid was a common guest at tea time. Fast forward to today, and the river supports over 125 species of fish, from bass to bream, a biodiversity triumph that shocked even scientists.
The clean-up started in the 1960s, when the Tideway tunnels and stricter sewage regulations began undoing 150 years of neglect. It worked—so well that in 2010, the first official river swim since 1837 was held, and it didn’t make anyone ill.
