She competed at the 2008 Beijing Olympics, where she finished 7th in the women's 10K race. She also swam at the 2008 FINA World Open Water Swimming Championships in Sevilla, Spain.
As a former pool swimmer turned marathon swimmer who overcame her trepidation of the open water, Okimoto was the silver medalist in the women's 10K Marathon Swim at both the 2007 and 2011 Pan American Games and won the overall title of the 2010 FINA 10KM Marathon Swimming World Cup series.
2011 FINA World Championships
Poliana placed 6th (2:02:13.6) in the 2011 FINA World Championships in the 10K Marathon Swim in Shanghai, China which qualified her for her second Olympics at the 2012 Olympic Games in London.