Marino was a midfielder at Massapequa High School, where he earned all-league, all-county and high school All-American honors as team captain. He also was the team's leading scorer and MVP.Bill attended Cornell University where he was a three-time All-American. Marino was selected to the first team in 1976, second team in 1975, and honorable mention in 1974. He set the record for goals scored by a midfielder in the Ivy League. In 1976 Marino was one of three team captains who led the Big Red to the NCAA Division I National Championship. He represented Cornell as team captain for the north in the 1976 North/South Collegiate All-Star game. He received the ECAC Scholar Athlete Award and was the first recipient of the Peter Baneker Award from the players at JHU as the outstanding opponent in 1976.
Marino played on the 1978 and 1982 U.S. teams and was team captain for the 1978 team. He played club lacrosse for the Long Island Athletic Club winning three club championships. He was elected to the Club All-Star team six times. He also played for the Brine Lacrosse Club. Marino was elected to the Long Island Metro Lacrosse Hall of Fame in 1991.
Bill's brother, Roddy, was elected to the National Lacrosse Hall of Fame in 2002.