Yusra Mardini fled Syria almost a year ago and is now part of a special refugee team at the games.
The 18-year-old was the first member of the 10-strong Refugee Olympic Team to compete in Brazil, winning her heat in the 100 metres butterfly.
Her time of one minute 09.21 seconds was not enough to earn her a spot in the top 16 and qualify her for the semi-finals, but her participation, less than a year after she risked her life by jumping into the Aegean Sea to help push a sinking boat of 20 migrants to safety, has provided one of the most inspiring tales of the Games.
"Everything was amazing," said Mardini, now based in Germany.
"It was the only thing I ever wanted was to compete in the Olympics. I had a good feeling in the water so I'm happy for that.
"Competing with all these great champions is exciting."
Mardini, and her sister Sarah, fled their Christian community in Damascus as civil war broke out in Syria and passed through Lebanon and then Turkey before their treacherous crossing by dinghy to the Greek island of Lesbos.
During the journey the boat's motor broke, leaving them stranded.
The sisters and another woman plunged into the water and took turns kicking and pulling the boat for three-and-a-half hours before eventually reaching safety.
Mardini added: "I've only been back swimming for two years so we're only now getting back to my levels of before. But I'm pleased."