Rio de Janeiro promised to clean up Guanabara Bay as part of its bid for the 2016 Summer Olympics, but that apparently hasn't happened.
One local pediatrician revealed to Andrew Jacobs of the New York Times just how bad the conditions are.
"Foreign athletes will literally be swimming in human crap, and they risk getting sick from all those microorganisms," Dr. Daniel Becker said. "It's sad but also worrisome."
This is one of many issues that has been raised ahead of the games. On Tuesday, The Associated Press reporter Stephen Wade shared a video of an open sewer located just 50 meters from the athletes' village.