It's not attractive to have a green swimming pool in your backyard, let alone at the Olympics. In the past two days, both the water polo and the diving pool in Rio have turned from a normal blue color to a dark green. FINA (the organization responsible for governing swimming and diving) said that some of the cleaning chemicals ran out and caused algae to grow. The Rio 2016 Local Organizing Committee has said that the water is safe and will not cause any problems for athletes. Some athletes are complaining, saying the water is affecting their ability. You can see the whole story, as well as some reactions on social media here.