On Tuesday the diving pool was green. Then on Wednesday, the water polo pool also turned green.
Now on Friday it appears that the diving pool has been closed to training altogether -- so as not to disturb the water and help it turn blue again.
"We confirm that diving training in Maria Lenk Aquatics Centre pool is canceled this morning," said Rio 2016 spokesman Philip Wilkinson.
"The reason is that the water must be still so the pool can return to its blue color as soon as possible."
Instead, athletes will be dry training -- usually involving trampolines -- with water training and competitions set to resume later in the day.
British bronze medalist diver Tom Daley tweeted his concern over the closure.
But Olympic organizers confirmed regular tests showed there was no problem with the quality of the water -- just the color.
Swimming pools, in case anyone is unclear, are supposed to be a shade of azure.
So, what is going on? There are many explanations.
A change in alkalinity:
Mario Andrada, the communication director for the Rio 2016 local organizing committee, says a sudden change in alkalinity is the culprit.
"We expect the color to be back to blue soon," Andrada said, adding there is "absolutely no risk to the athletes or anybody."
An algae bloom:
Nope, the green tone seen was due to a proliferation of algae, the organizing body said. The algae bloomed because of heat and lack of wind, it said.
Nope, says, FINA, the blames lies with the organizers. FINA -- the international governing body for swimming, diving, water polo etc. -- claims water tanks "ran out of some of the chemicals used in the water treatment process." It made no mention of wind or heat.
The Internet dives in
It didn't take long for the Internet to offer up its own imaginative take on the green shade.
Commenters joked that it was nice of Shrek to loan his home to the Olympics, while others shared pictures of Kermit the frog and swamp monsters.