I know you already saw some of my comments to others' answers/comments, but I didn't answer your question "officially" because I never had aspirations to be a pro. But I was a sprinter on my school's track teams. That would probably be the sport, if I had wanted to be a pro.
Yet, also, synchronized swimming always intrigued me. And, during my undergrad years, I was the very first male to ever take the synchronized swimming course at the university in which I was enrolled. It was incredibly challenging and physically demanding. In no way would I have made it as a pro, ha! :)