Before USMMA: Marionakis earned varsity letters in volleyball, softball, swimming, and weightlifting while attending Royal Palm Beach High School.  She served as captain of the volleyball team in her senior year as well as being a second-team all-conference selection in 2010, 2011, and 2012.  Marionakis was also named team MVP and received the Coach's Award as her team won a District Championshp and finished second at regionals.  She is a member of the National Honor Society and ranked 12th in her graduating class.