In January 2021,
USA Swimming announced its decision to break the Olympic trials into two meets called waves. This decision was made in part to follow social distancing protocols and keep attendees, athletes, and workers safer during the COVID-19 pandemic. Each wave had a different set of qualification time standards. The time standards took effect January 28, 2021 and an initial qualifying period for both waves ended May 30, 2021. Wave I swimmers who met the time standards for Wave II at the Wave I meet and finished first or second in their event qualified to compete at the Wave II meet. A total of 50 swimmers from Wave I qualified to compete in Wave II. The first swimmer who swam in the Wave I meet and advanced to a second swim, semifinal or final, at the Wave II meet was Heather MacCausland in the women's 100-meter breaststroke on June 14, 2021. The most watched
YouTube video from the entire Olympic trials came from Wave I not Wave II. It was a clip of
Kayla Han winning the B-final of the women's 400-meter individual medley and breaking a USA Swimming national age group record in the process. Between Wave I and Wave II, 2,285 individuals competed at the 2020 Olympic trials, a decrease of over 700 swimmers from the
2016 Olympic trials. As a whole, proportionally fewer Wave I swimmers and proportionally more Wave II swimmers swam faster than their seed times compared to swimmers at the 2016 Olympic trials. ==Events==