Hendrika "Rie" Wilhelmina Mastenbroek (26 February 1919 – 6 November 2003) was a Dutch swimmer and a triple Olympic champion.
Born in Rotterdam, she started swimming under the coaching of "Ma" Braun, who had coached her daughter to an Olympic gold medal in 1928. In 1934, Mastenbroek won three gold medals and a silver at the European Championships.
She repeated that performance at the 1936 Summer Olympics, aged only 17, winning the 100 m freestyle, 400 m freestyle and the 4×100 m freestyle. In the 100 m backstroke, she finished second behind teammate Nida Senff. (Senff missed a turning point and had to swim back before completing the last 50 m. She nevertheless beat Mastenbroek thanks to an outstanding last leg.)
The following year she became a swimming instructor, thereby losing her amateur status and becoming ineligible for competition.
During her career she broke nine world records (six for backstroke and three for freestyle). In 1968 she was inducted into the International Swimming Hall of Fame. In 1997 she received the Olympic Order.
Mastenbroek is a polder in the Dutch province of Overijssel. It lies north of the city of Zwolle. "Mastenbroek" is also the name of a small village, built around a church in the middle of the polder.
The polder is part of three municipalities: the western part, including the hamlet Bisschopswetering and half of the village of Mastenbroek, lies in Kampen; the southeastern part lies in Zwolle; and the northeastern part, including the hamlet of Nieuwe Wetering and the other half of the village of Mastenbroek, lies in Zwartewaterland.
Coordinates: 52°34′30″N 6°1′25″E / 52.57500°N 6.02361°E / 52.57500; 6.02361
Mastenbroek may refer to: