The weather was mild, although it could hardly be described as balmy.
One entrant described the water as "freezing".
There was a variety of innovative costumes - including Santa Claus - although the more sensible opted for wetsuits rather than bathing suits.
Money raised went to the Oamaru Rowing Club.
• In Wanaka, the midwinter action was on the water, rather than in it, as several water-skiers and wakeboarders marked the shortest day with an icy circuit on the glassy lake behind a fast boat.
A large group of local residents gathered on the shores of Lake Wanaka to watch the fun.
The event has become something of a Wanaka tradition to celebrate the shortest day of the year and has grown into a popular outing down through the years, for residents and visitors alike.