If you spot heads bobbing in the Hauraki Gulf this morning, don't be alarmed.
Thirteen swimmers are facing the cold and swimming 20km from Matiatia Bay on Waiheke Island to Mechanics Bay in downtown Auckland.
The swimmers are raising money for the Auckland Westpac Rescue Helicopter, which flew to Waiheke Island to pick up sick and injured patients 232 times last year.
Of 1060 helicopter missions last year, that represented 22 per cent, making it the helicopter's second-most visited region.
The group's fundraising target was $20,000, which they have already surpassed with this morning's total just over $29,000.
The money already raised has paid for three missions to Waiheke.
The group set off just after 7am and are expected to arrive about midday.
Coping well with the chop, swimmers have had their first feed and still going strongPosted by Chopper Swim Challenge on Wednesday, March 30, 2016
Seven members of the team were to swim the entire distance, and others were in teams sharing the swim.
The idea for the swim was hatched by Westpac risk manager Olaf Adam mid last year after he became hooked on ocean swimming. He and colleagues Michael Buck and Dean Madsen felt the swim would provide a perfect opportunity to raise awareness of the important service the chopper provides. It operates 24 hours a day, seven days a week, 365 days a year.
Waiheke has a resident population of almost 10,000 who rely heavily on air ambulance services and, as a not-for-profit entity, the helicopter relies heavily on community and corporate support.