Karine Thomas is the lone holdover from the 2012 Olympic synchro team that narrowly missed the podium in London, finishing fourth. After competing at the World Junior Championships in 2006, Thomas joined the national team in 2007 and made her debut at the FINA World Championships that year. She helped the team to fourth place finishes at the next two world championships. She was also a member of the team that won gold at the 2011 Pan Am Games.
After a lot of turnover on the national team post-London 2012, Thomas began competing in the duet competition in 2013. In 2015 she and Jacqueline Simoneau won duet gold at the Pan Am Games in Toronto, where they were also part of the gold medal-winning team. She went on to compete in both duet and team at the 2015 FINA World Championships. The duet got their ticket to the 2016 Rio Olympic Games, where they finished in 7th place. The pair swam together for the last time at the 2017 Canadian Open as Karine announced her retirement afterwards (read press release here).