As you probably know, pool water is supposed to look clear. However, an Olympic diving pool in the Maria Lenk Aquatics Centre at the 2016 Rio Olympics turned an unnatural green on Tuesday and forced at least a few Olympians, like British diver Tom Daley, to wonder WTF was going on with the water, which looked like it belonged in a swamp instead of an Olympic facility:

So what has caused the water to turn green so suddenly, you ask? Are all of those urban legends that were told to you by people who didn't want you peeing in their pool—gasp—real? Well, no.

The Olympic organizers and FINA—the international governing body of swimming, diving, water polo, synchronized swimming, and open water swimming—have spent the last 24 hours trying to figure out the issue and, as it turns out, the problem is one that swimming pool owners have been trying to combat for years: algae. In this situation, the algae is growing because of the heat in Rio and the lack of wind in the facility. This has resulted in problems with the pH level of the water, which—without going into a bunch of boring details about water chemistry—is all out of whack right now and causing the water to turn green.

Fortunately, FINA has put out a statement to let Olympians know that there aren't any health risks associated with the green water.  "The pH level of the water was outside the usual range, causing the discoloration," the statement said. "The FINA Sport Medicine Committee conducted tests on the water quality and concluded that there was no risk to the health and safety of the athletes, and no reason for the competition to be affected."

But it looks like the water is still presenting a problem for Olympians. It affected the divers who took part in the women's synchronized 10-meter event on Tuesday:

And despite the fact that the water in the diving pool was then treated, it still looks green on Wednesday—and the water polo pool located next to it has started to turn green now, too:

This really sucks for the Olympians, but people on Twitter are sure enjoying it. At some point, we imagine the water will be completely clear again, but until then, the jokes and memes are out in full force:

Jumping into a green pool isn't the worst thing in the world (things could be worse, Olympians!). But it's pretty amazing to see what's supposed to be a world-class Olympic facility struggling to keep pool water clear.