Glenwood has enjoyed 3 golden periods of Water Polo. In the period 1977 – 1982, the 1st team lost only two games out of 95 played during this 6 year period. From 1985-86 40 games were played, of which only 3 were lost. The third period occurred during the year 1997-98 when only 2 of the 37 local games were lost. For these 2 years, the 1st Water Polo team were ranked 2nd in South Africa, behind St Stithians.
In each of these periods, the team was fronted by a player of exceptional talent, namely Derek La Marque (1976-79), Hayden Mottram (1980 – 82), Craig Roy (1984 – 86) and Donn Stewart (1995-99).
The school has produced 7 Springboks, namely Donald Campbell, Derek La Marque, Guy Mottram, Craig Roy and more recently Donn Stewart and Darren de Bruyn in addition to countless provincial players such as Darren Stone, Grant Robertson, Bradley Smith, Scott Brown and Pierro Ioppo.