Uh oh, now the water polo pool has turned green too! But we've finally found out why...

The biggest mystery of the Rio Olympics so far has just taken a new twist.

Just when you thought the green diving pool story couldn't go any further, the water polo pool has turned green too.

But no fear, we've found out why the water turned such an alarming shade - and no it wasn't because someone used it as a toilet.

Fina - the international swimming federation, responsible for administering competitons like the Olympics, said the following:

"Fina can confirm that the reason for the unusual water colour observed during the Rio 2016 diving competitions is that the water tanks ran out some of the chemicals used in the water treatment process."

Yes, you heard that right. The Olympics ran out of chemicals for two pools. Two pools. At the Olympics.

Fina said that testing had been done on the water, and though the lack of chemicals meant "the PH level of the water was outside the usual range", there was no risk to the health and safety of the athletes.

Try telling that to the Australians though - they complained of itchy eyes after their water polo event.

"It hurts at the end of the game and we'll probably get teary eyes for the next couple of hours but that's all right. It wasn't too bad in the water but now it's really starting to sting," Australian centre back Richie Campbell told Fairfax after his match with Japan on Wednesday.

Tom Daley is looking at the positive side though - the green pool means it's easier to "know which way is up".

At first we thought Tom probably shouldn't be diving if he doesn't know his up from his down, but then he explained.

"When you're spinning around diving, outdoor diving can be difficult because the sky is blue and the water's blue, so you don't know which way is up. Now that the water's green it makes it slightly easier to see where you are," he told ITV News.

He added: "I've seen way worse, trust me."