Rio Olympics: Diving Pool Turns Green, and U.S. Swimmers Find Gold

Malaysian divers Cheong Jun Hoon and Pamg Pandelela Rinong compete in the final of the women’s synchronized 10-meter platform final Tuesday. CreditJames Hill for The New York Times

An unsettling thing happened at the Olympic diving pool on Tuesday: the water inexplicably turned green, just in time for the women’s synchronized 10-meter platform diving competition.

Officials said they did not know what caused the trouble, exactly. But they declared the water had been tested and was not dangerous. It was an unsettling sight, appearing to become greener and murkier as the day went on, having been a lovely light blue on Monday.

The British diver Tom Daley, who won a bronze medal in the same pool the day before, posted a photograph on Twitter showing the contrast between the colors of the pools. “Ermmmm – what happened?” he said.

The adjoining pool at the aquatic center, used for synchronized swimming and water polo, remained its normal blue color, which made the extreme greenness of the diving pool all the more striking.

Meanwhile, diving practice went on as planned, and so did the women’s synchronized event. Competitors generally said that the swampiness of the water did not put them off their form, although they found it weird and puzzling.

“I’ve never dived in anything like it,” said Britain’s Tonia Couch, who finished fifth, along with Lois Coulson.

Here is the full article, including an interview with a pool repairman in California who has some ideas about what might be causing the greenness.