Diving official believes the green water in Olympic diving pool was caused by algae

Matt Dunham/AP

Hours after the water in Rio's Olympic diving pool turned a mysterious and unsettling shade of green, a Canadian diving coach speculated to the AP on Tuesday that the water discoloration was likely the result of algae.

"Everybody was scratching their heads going, 'What's going on?'" Mitch Geller said. "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."

It may not have been toxic like several of the other bodies of water in Rio, but the green color was nevertheless worrisome during the women's 10-meter diving final. Compared to the perfectly blue water in the water polo pool just across the pool deck, the diving water seemed extremely unpleasant.

Here's the contrast:

Matt Dunham/AP

Compared to the two pools just one day before:

Dean Mouhtaropoulos/Getty

Although the green water was ultimately not harmful, some divers still said they made sure not to open their mouths.

"The only thing we said is don't open your mouth in the water, just in case," bronze medalist Meaghan Benfeito said afterwards.