Rob Groen, a member of Groningen’s student rowing club Aegir, primarily rowed in the single sculls. His peak was in 1963 and 1964. In both years, he won the national single sculls classic, the Holland Beker. In both years, he also claimed a silver medal in the European Championships. In 1963, he finished behind Václav Kozák and in 1964 behind (then) two-time Olympic Champion Vyacheslav Ivanov. These results qualified him for the Tokyo Olympics, but he performed poorly and did not make the final. In the B-final, he did record the fastest time of the tournament. Groen retired after these Games, but remained active as a rower and coach.