Significant work will be required to fix the Far North's Tūtūkākā Marina, which was severely impacted by strong surges after the eruption of underwater volcano Hunga-Tonga-Hunga-Ha'apai in the Pacific.
Yesterday, a tsunami advisory for the north and east coasts of the North Island was issued after underwater volcano Hunga-Tonga-Hunga-Ha'apai erupted and triggered a tsunami in Tonga.
Police said emergency services received a number of calls from people based in the Far North between 11pm and 12am, including Te Rere Bay and Shipwreck Bay.
More than 120 people were evacuated last night due to the powerful waves.
Police, Fire and Emergency, and Coastguard also assisted with evacuations of boats moored at Tūtūkākā Marina last night.
Northland regional harbourmaster Jim Lyle said today that sections of the marina had broken off, piles had been pulled out of the seabed and a number of vessels had sunk.
Two teams were working to assess the damage on Sunday and secure debris that was still floating around.
"Obviously, there's quite a bit of damage to the marina structure. They've lost quite a few whole fingers and various sections of the marina have been ripped off and the fuel jetties sunk, and there's at least 20 piles that are totally gone."
Lyle said six vessels had sunk, the largest was around 16 metres long.
The initial destruction was caused by one wave, which came through the marina around 11pm on Saturday. It was followed by several surges that continued into Sunday.
The clean-up would require cranes, barges and dive teams and would take some time, Lyle said.
Diesel and oil spills were a risk with sunken vessels and fuel was being removed off some of the at-risk vessels.
Lyle said the geography of the Tūtūkākā marina meant it was often affected by tsunami, but this was the worst damage he had seen.
"It's a narrow entrance and an enclosed bay, it's not an estuary so there's nowhere for the pressure to go."
There is a tsunami warning system in place but Lyle understood marina residents were not alerted before it struck.
No damage has been reported at Northland's other marinas in Whangārei, the Bay of Islands or Whangaroa Harbour.