The controversially non-blue colour of the Olympic diving pool at the Maria Lenk Aquatics centre in Rio has sparked puzzlement, wonder and a little distaste from viewers across the world.
As the world waits for an official answer to "why is the pool green", people have let their imaginations run wild. Here are some of the most weird, wonderful and worrying of their theories.
1. Pee, obviously
Olympic Pool.It turned green because someone peed in it. Blue water+yellow pee=green water.
-- John Brown's Body (@Amandaloutfi) August 9, 2016
If there is anything at all you learn from primary school art, it is which colours mix. Blue plus yellow equals green, you can't argue with that logic.
This theory has been called into question by pool experts however, with Brett Blair telling The Guardian newspaper the Olympic pool was "way too big" for urine to affect its colour.
Although maybe the experts hadn't considered it could be super-pee the pool is dealing with ...
-- Drew Johnston (@drew_j) August 10, 2016
2. It's jelly
-- French ? George (@Lv_poet) August 9, 2016
If your favourite part of birthday parties when you were eight was the dessert, you will probably have dreamed of having a pool filled with lime jelly.
Adding Jell-O mix to a pool is a prank as old as the dessert itself (it was invented in 1897, apparently) so surely this is the explanation for the pool's greenish hue?
Senior prank we're filling the pool with green jello
-- The Nick Foltz (@FoltzDaddy) November 8, 2014
3. It's jealous
-- Damo BlueHeavenBerry (@Strauchanside) August 9, 2016
Ever since Shakespeare described it as the "green-eyed monster", everyone knows the colour is associated with envy and jealousy.
In similarly romantic fashion, perhaps the pool is just feeling green?
Perhaps the Olympics pool has turned green because someone told it what lovely Clare Balding earns.
-- abz byrne (@abzbyrne) August 9, 2016
4. Alien activity
-- Fred the Alien (@fredthealien316) August 10, 2016
Whether or not this cryptic message from "Fred the Alien" amounts to a confession is unclear, but some definitely think the pool's colour is extra-terrestrial.
do we know why the pool was green yet or do I need protection from the aliens
-- Freya (@_freyalewis) August 9, 2016
Some even have theories as to exactly which alien life we might be dealing with here.
-- Ricky Mar (@rickymar) August 10, 2016
5. Gremlins, definitely gremlins
Others think it's those pesky little creatures from the 1984 classic sci-fi comedy, Gremlins.
They even offer evidence, showing this would not be the first time they turned water green ...
6. Because of Brexit
No 2016 conspiracy theory list would be complete without relating the whole thing to Britain's vote to leave the EU.
A month-and-a-half on from the historic vote, many of those opposed to the move are still insistent it is the root cause of all things bad or unnatural in the world. Rio's pool is no exception.
-- Go Go Gorilla (@Tax_Evader) August 9, 2016
7. Brazilian patriotism
This fantastic theory claims the Olympic diving pool has turned all patriotic and taken on the colour of Brazil's national flag.
Whether this change in colour has deliberately been done by someone or is a spontaneous miracle is not clear, but then neither is the pool.
Seriously guys, the Diving pool is GREEN! Is that some sort of tribute to the Brazilian flag?
-- Sigrid (@mirrorhands) August 9, 2016
Not 100% sure which media outlet first reported the diving pool turning green, but I think it was Algae-Zeera
-- u??ssnS ???W (@suss2hyphens) August 9, 2016
Perhaps one of the more common theories surrounding "greenpoolgate" is it's algae causing it all.
These simple plants are certainly green, caused by the amount of chlorophyll they contain which they use for photosynthesis. However it's how the algae got into the chlorinated pool which is the puzzling thing.
Some on Twitter, those who probably have been to see the new Finding Dory movie at least once, theorise perhaps there are some scheming sea creatures responsible ...
-- Sophie Roberts (@SophRobo_) August 9, 2016
9. The Olympic diving pool is actually a blonde person
-- princess (@hailsrenae) July 4, 2016
So according to chemistry nerds it is not actually the chlorine in the pool that turns blonde hair green, but copper. Unlike the brown oxidisation of iron, copper turns green. According to about.com the oxidised metal in the pool bonds to the protein in the hair.
So maybe the diving part of the aquatics centre is just having a bad hair day? Or perhaps this strange personification of the pool is actually a thinly disguised and genuine scientific theory for the pool's colour change?