Forget about medal-hog Michael Phelps wrecking the gaff and a fencer losing his mobile phone during a joust, this was the talking point of Rio 2016 on Tuesday night.
During the pool diving competitions, fans were surprised to see the water gradually go from blue to sickly green as the day went on.
Team GB diver Tom Daley summed up the thoughts of the watching world after he had completed his heats...
https://twitter.com/TomDaley1994/status/763089368022192129
As viewers offered a variety of possible explanations, it seems that the actual reason for the change of colour has now been identified. Bloody algae.
Mario Andrada, a spokesperson for the Rio organising committee, explained to reporters last night, that the green tinge was caused 'by a proliferation of algae'.
Typical algae, proliferating around like it owns the place.
The stillness and heat of the day didn't exactly help matter, either.
Andrada commented:
"This was because of heat and a lack of wind. We did all the chemical tests. The pool will be blue tomorrow.
"If it were green and yellow, we would know it was a patriotic thing,"
One to watch closely today as the pool action continues.
Andrada can then go back to figuring out if a bus carrying media through the Deodoro zone, last night, was hit by stones or bullets.
