A police spokeswoman told the Herald the dive squad arrived at the popular swimming hole around 8pm.
At 10.40pm, the spokeswoman said the dive squad was still in the water at Hunua Falls.
Elsewhere, a man who failed to surface after going underwater at a swimming hole in Ramarama sparked another search and rescue operation.
The incident is believed to have occurred at Maketu Waterfall, off Pratts Rd, around 4.50pm.
Emergency services spent the afternoon searching for the man.
The police divers were also expected to try to help find him.
The police spokeswoman said lighting was put in place to assist in the search and "all going well the squad will get to both incidents tonight".
Hunua Falls: beautiful but dangerous
The falls are found to the southeast of Auckland city but their scenic setting provides a mask over their dark history.
The waterfall is 30 metres high and the pool beneath is almost 20 metres deep, featuring a steep drop-off where many swimmers have come into difficulty.
In 2016, two teenagers died at the popular swimming spot in separate incidents, prompting calls for Auckland Council to restrict access.
Peter Lemalu, 17, and Lilatoni Vetemotu, 13, both died at the falls within several days of each other.
Their deaths resulted in a plea to close the swimming hole, but that was unsuccessful.
In April 2016, Auckland Council parks manager Mark Bowater told the Herald there were no plans to fence the falls or assign lifeguards.
"It's an incredibly scenic, beautiful spot [but lifeguards] are not being seriously considered, so there's no fundamental change to the site."
He said using lifeguards would send the message that people were encouraged to swim there, when the council recommends people avoid doing so.
Several combining factors make the falls hazardous to swimmers.
Bowater said the extreme variations in depth meant swimmers could go from waist-deep water around the edge to depths of up to 19m in one step.
"We've got very deep water there, that's one of the main hazards.
"There's a sharp drop-off from the edges. There are some shallow edges that are quite visible and there are even rocks where you can cross from one side to the other but they are slippery.
"You've got a sharp drop down to that deepest point."
As fresh water hits the pool from the falls' 30m drop it aerates, making it less buoyant.
While there are no known deaths at Maketu Waterfall, a woman was rescued early this month after falling down the waterfall.
The woman, in her 20s, was winched out of the pool by the Westpac Rescue Helicopter on January 6.
She sustained "multiple injuries" during the fall and was flown to Middlemore Hospital in a moderate condition.
