About 50 Scarborough Dippers plunged into the 8 deg C water as part of the annual Wet July challenge.
Members pledge to dip in the sea every day of the month, wearing just togs and a smile - rain, hail or shine.
Scarborough Dippers co-founder Sandra Taylor said soaking up the super cold winter water was therapeutic.
"It's really stimulating, I mean, it's really challenging to get in there and I think once you've dipped, everything else in the day feels a bit easier."
The Scarborough Dippers are hoping to raise $8000. That money would go to Sumner-based mental health surfing initiative, Surf Ora, and installing a defibrillator at Taylors Mistake.
"Last year, we actually put a defib down at Scarborough, and we're really humbled by the fact that it actually saved somebody's life this year."
"We've become quite a movement now.
"Most of us go every day throughout the year."
Most of the members range in age from their 40s through to three dippers in their 80s.
"It's really gratifying to see how much people get out of it, they really get a thrill.
"And I think the big thing is we have created a community and that's what I'm most proud of."
The swimmers finish off their daily icy cold plunges by dipping their feet into a bucket of warm water they affectionately call the Bucket of Joy.
And they're determined to keep up the winter challenge through to the end of the month, for the social fun, and the reward of raising money for a few good causes.
- To find out more about the Scarborough Dippers and Wet July, visit www.facebook.com/scarboroughdippers
- By Geoff Sloan, made with the support of NZ On Air
