Spoiler: It wasn't early St. Patrick's Day celebrations
Whatever caused the diving pool at the Rio Olympics to turn green, has spread to the polo pool beside it.
Spectators and athletes were greeted by the rather unusual sight of the coloured water on Tuesday, and so far it has been somewhat of a mystery.
There had been speculations that algae may have been the cause, but officials have blamed a 'chemical imbalance' in the water which is now affecting the adjacent pool.
Can't fix the diving pool? Make the water polo pool look the same. pic.twitter.com/z9vBMRE0pP— Edwin Jongejans (@Leedsajax) August 10, 2016
Rio 2016 spokesperson Mario Andradas told The New York Times: "Midafternoon, there was a sudden decrease in the alkalinity in the diving pool, and that’s the main reason the color changed."
Due to the large volumes of people in the water in the past week, their presence may have resulted in changes in the water's chemical balance.
He said the water had not been monitored as carefully as it should have been and rain on Wednesday morning exacerbated the problem.
Tests carried out showed no health risks to athletes however, and officials say the water should change back to blue today or tomorrow once the chemical balance have been restored.
"It will be blue from now on," said Andradas.