Three Greenpeace protesters who had been chained to a supply vessel in Port Taranaki have been removed and arrested.
Two others others remain locked to a mast on the tender vessel Mermaid Searcher.
Greenpeace said protesters would stay there as long as it takes to get their message across - that it's time to stop the search for oil and gas.
The protestors boarded the Mermaid Searcher in the early hours of the morning and locked themselves to a mast and railing in protest at the oil exploration ship the Amazon Warrior, which the tender supports.
The Amazon Warrior has been operating off the Taranaki coast for the past three months.
Greenpeace campaigner Amanda Larsson said seismic surveying was harmful to marine life.
"It's blasting the seabed every 10 seconds, 24 hours a day, seven days a week on the hunt for oil that we can't actually afford to burn anyway because of the effects of climate change."
Port Taranaki chief executive Guy Roper said protestors have been issued with trespass notices.
Mr Roper said the port was concerned about the protesters safety and that of port staff and the police who had to deal with them.
"There is forecast bad weather approaching therefore disembarking them from the vessel quickly and safely is our focus and we are supporting the police to achieve this."
The police were also monitoring a small group of Greenpeace supporters on the Lee Breakwater at the port.