Harrison Merrill established his swimming career at the Atlanta Swim Association under Coach Pete Higgins by setting multiple age group records. As only a fourteen year old, Harrison finished sixth in the United States Nationals in the 1500 meter freestyle event. While attending Westminster Schools, Harrison received Prep All American Honors seventeen times. Harrison continued his swimming career at the University of North Carolina where his team won several ACC championships and he won individual titles in the 100, 200, and 500 yard freestyle and the 400 yard individual medley. He also received
several All American Honors while at UNC and the Patterson Award which is given to the most productive male and female athletes each year.