From glimmering blue to murky green, the water of the diving pool at the Maria Lenk Aquatics Centre in Rio Olympics has led to a mass of wild theories. But what has really caused the sudden change of color?

On Tuesday, British diver Tom Daley shared on Twitter an unsettling image, showing the discoloration, which happened overnight. The left part of the photo shows an azure-colored pool while the other side shows a green-colored one.

Despite the discoloration, Rio officials said there is nothing to worry about as the water has already been tested and results showed the color poses no risk for athletes.


Although officials have not formally announced the real reason behind the discoloration, one Canadian diving coach suspected it might have been because of algae formation.

"Everybody was scratching their heads going, 'What's going on?'" Mitch Geller told Associated Press in an interview.

"I think that the filter is busted, but I'm not sure. It's not really dangerous. It's not like it's toxic or dirty or any of that. It seemed to get worse over the course of the competition."

In the same article, Rio spokesman Mario Andrada also said the green was caused "by a proliferation of algae."

"This was because of heat and a lack of wind," he said.

Meanwhile, Canada's Meaghan Benfeito who took a plunge into the water for the women's leg said the color of the water actually helped her win.

"It's not the same color as the sky so that was really on our side today," Benfeito told Business Insider.

Algal bloom usually occurs in rivers, lakes and beaches, but not in pools. In Florida, slimy green beaches have been present since early 2000. The algae or cyanobacteria come from Lake Okeechobee, which is Florida's largest freshwater lake. The outbreak has been driving away tourists and has been degrading the water quality in Florida waters for the past years.