"Each time I sold a paddle board, I would mention it to them and it just grew."
The group now has up to 40 paddlers ranging from 11-year-olds to those in their 70s, with the biggest age group the 50-70-year-olds.
The 4.1km races start at the Canopy Bridge, through Te Matau A Pohe bridge and back with different races based on ability levels.
"Everyone likes to race, you can't help it – if you're in the last place, you still want to try and catch the person in front of you and if you're in second to last, you don't want the person behind to catch you.
"It's a great way of getting fit and trying to beat your time."
Riverside SUPers also host the annual Bridge to Basin challenge, which attracts world champs who pass on tips to fellow paddlers.
"We race all year round and, in winter, we wear flashing lights. If someone new shows up – they are shown techniques – and, at the end, we load our boards onto the cars and go and have a cold one and something to eat at The Quay."
Riverside SUPers meet at the Town Basin car park every Tuesday for a 5.30pm race start.