The 2016 Rio Olympics are finally underway. After months of worrying about Zika , Brazil's water quality, and a host of other issues, the world's best athletes have converged in Rio. It's still reportedly a mess : the Olympic village is unfinished, the water is still unsafe for swimming, and there isn't even coffee . Yet, athletes are overlooking these issues to put on the best showing for their countries.They're competing for their native country's respect and those medals.While the Olympics are all about sports, some celebrities, many of whom happen to be athletes, are also partaking in the fun. Serena Williams, Gisele Bündchen , Michael Phelps, and a legion of other celebs presented, carried the Olympic torch, or held their country's flag during the opening ceremony and events leading up to the big show.Many of them are sharing the beauty of the Olympics on Instagram. Here are some of the most stunning celebrity photos.