Recreational boaties in the Bay of Islands are being asked to take extra care on the water during the State Paihia Classic on Saturday 10 November.
More than 800 swimmers are expected to take part in the annual Russell to Paihia swim which the Far North District Council is sponsoring for the fourth time.
Event director Scott Rice is asking harbour users to look out for swimmers who will leave Russell Wharf at 9:30am and take about two hours to complete the 3.3 km crossing.
"It is very important that others on the water cooperate with race officials and if possible change their schedules to stay clear of the race area for the duration of the event," Mr Rice says.
Six inflatable rescue boats and 18 Surf Life Saving New Zealand lifeguards on ski boards will escort the swimmers during the crossing.
Crews aboard two Thundercat Racing New Zealand boats will warn boats approaching swimmers to head between Russell beach and a white Fullers GreatSights jet boat that will tail the last swimmers and open the channel for normal use.
"The field should be fairly concentrated in the early stages, but obviously as the swimmers move across it will become wider spread."
Boaties are also asked to take care around Paihia where three shorter swims will be held just off the beachfront at 11:45am (1000m), 12:35pm (300m), and 12:40pm (200m State OceanKids).
"If it is possible to plan around the event and avoid that area altogether while the races are on, that would be even better," he says.
A 2000-metre triangular course off Paihia Beach will be used for the 3.3km swim if unsafe ocean conditions force the cancellation of the Russell-Paihia crossing.