Most of the time, as they do on patrol at the beach, the lifeguards see the potential for an accident and take what they call preventive actions.
This could be warning off pleasure craft which stray into restricted areas and revellers who are too close to the edge of the wharves - a long drop to the swift tidal current flowing in the shadows.
On Saturday night, a sharp-eyed crew spotted trouble on shore. They clambered up a ladder to help a person who was having an epileptic fit on the wharf.
Mr Witten-Hannah and supervisors Andrew Shaw and Ollie Irwin are from the Karekare Surf Life Saving Club and the other supervisor is Rob Pidgeon from the United North Piha Club.
The Karekare club organised the service but the lifeguards are drawn from all other Auckland clubs.
"They have made a superb effort often in cold wintry conditions to ensure that visitors have a margin of safety in the event of falling into the Waitemata Harbour," said Waterfront Auckland chairman Bob Harvey, who is also president of Surf Lifesaving.
When fan zone planning began, Mr Harvey and Rugby World Cup Minister Murray McCully asked Surf Lifesaving Auckland Northern Region for a water safety overview around the wharves.