Carolyn first represented Ireland at water polo. She later dominated the domestic triathlon scene but only made her international debut in 2014 at age 26. She is a doctor but put her medical career on hold in 2018 to train fulltime. Her first World Cup podium was silver in Kazakhstan in 2019 when she was also 6th at Europeans. In 2021 she was second, behind Olympic champion Nicola Spirig, at the World Cup in Lisbon in May and 10th at the World Championship Series in Leeds in June.