For the past day or so, everyone talking about the mysterious, murky green diving pool at the Rio Olympics contrasted it with the adjacent water polo pool, which was a crystal-clear blue. But it was too good to be true.
As Rio’s local organizing committee told Quartz that they had treated the diving pool and expected the color to return to normalcy, they did not mention that the water polo pool next door had started turning a shade of green by this morning men’s water polo matches. Why did the color spread from the diving well to the water polo pool? Probably the same reason the diving pool turned green in the first place.