The water in a Rio de Janeiro Olympics diving pool turned green Tuesday.
While visually questionable, venue officials at Maria Lenk Aquatics Centre said it presented "no risk" to divers, per Nick Hope of the BBC.
The difference in color was noticeable. Take a look at this side-by-side comparison from Matt Majendie of the London Evening Standard:
It's likely a simple case of not enough chlorine, but it's still somewhat concerning.