Lateral channel markers in Whitianga and Tairua harbours on the Coromandel Peninsula have been repositioned after they were moved by strong and unusual currents created by the weekend's Hunga Tonga–Hunga Ha'apai eruption.
Waikato Regional Council maritime officers found several inside the Tairua marina.
Buoys and beacons help guide boaties through shallow water, busy channels and past hazards. They are the "road signs" on the water and the different shapes and sizes communicate important information about what side is safe to pass on.
Each mark has its own unique colour, top mark and shape, and at night most will also have a light with its own unique colour or flashing sequence.
Regional harbourmaster Chris Bredenbeck said it was important to get the markers back in place.
"We had a number of buoys that had been lifted up by the currents and dragged into and around the harbours by the surges. Whitianga and Tairua are popular harbours, especially at this time of year, so it was important we got out there to relocate the channel markers as soon as we could."
Maritime officers in three vessels surveyed the locations of the channel markers within the harbours and returned those that had moved back to their correct positions.
"There have been a lot of extremely unusual currents running over the last couple of days and we're fortunate that we didn't get the same destructive impacts as up north," Bredenbeck said.
A red lateral port marker and a yellow 5 knot speed marker that mark the entrance to Whitianga harbour were expected to be recovered from the middle of the bay off Brophys Beach in Whitianga this week.
Bredenbeck urged boaties to remain extra vigilant when navigating the waterways.
Anyone who notices navigational hazards or buoys that are not where they should be is asked to contact the Harbourmaster's Office on 0800 800 402.