High school

A 2008 graduate of College Park High School in Pleasant Hill, California, Seidemann competed on their water polo team all four years of high school, and competed for three years on the swim team. She also played soccer as a preparation. Seidemann captained the water polo team in 2007 and 2008, and helped lead her team to a DFAL title as a senior, then being named a NISCA All-American, and Team MVP in 2007. She then went on to be a member of the U.S. Youth National Team in 2006, which won the gold medal at the Pan-American Junior Games, being the leading scorer in the tournament with 20 goals. Seidemann was also a member of the Youth National Team, going undefeated in Sydney, Australia the summer of 2007. She was also on the team that competed in the 2008 Global Championships. Seidemann earned All-America honors at the U.S. Water Polo 20/U Nationals.^[1]

College

Seidemann joined the Stanford University women's water polo team in 2009. As a freshman, she led the team with 59 goals, scoring at least four goals in a game on five separate occasions. She led Stanford in scoring again the following year, and was nominated to the ACWPC All-America First Team in 2010. In 2011, Seidemann had her third-straight 50-goal season, finishing second on Stanford with 51 goals. She also scored what proved to be the winning goal in the NCAA Championship title game.^[1]

Seidemann took a leave of absence from Stanford in 2012 so she could train with the U.S. national water polo team,^[1] but graduated in 2013 with a degree in psychology. In 2023, Seidemann was inducted into the Stanford Athletics Hall of Fame.^[3]

International

Seidemann first started playing for the U.S. national team in 2010. She scored three goals in that year's FINA World League Super Final and two goals in the FINA World Cup, helping the U.S. win both events.^[4]

The following year, the U.S. won the FINA World League Super Final again, with Seidemann scoring twice. She scored 11 goals in the Pan American Games, ranking third on the team, and the U.S. won the gold medal and qualified for the 2012 Summer Olympics.^[4] The U.S. went on to win gold at the Olympics as well.^[5] She was also part of the 2016 US olympic team, winning her second Olympic gold medal that year.