A search is resuming on Tuesday for a Department of Conservation (DOC) volunteer missing on Raoul Island in the Kermadec Island group, 1000km northeast of New Zealand.
The man is believed to have been swept into the sea while carrying out routine meteorological readings on Raoul Island around 6am on Monday.
The Rescue Coordination Centre of New Zealand (RCCNZ)is sending a long-range helicopter at 10am on Tuesday to search for the missing man. It is expected to take five hours to reach Raoul Island.
"He was down at Fishing Rock taking sea temperature readings. The vehicle he used to go down there was at Fishing Rock, the thermometer was in the water," Tim Brandenburg from DOC said on Radio New Zealand.
"Raoul Island is a small island in the middle of a very big sea. The sea conditions are often quite rough. There isn't any natural harbour, or shelter really," he said.
The helicopter will refuel on the island and search the coastline.
The six staff and volunteers remaining on the island have been doing everything possible to help find their workmate and are distraught.
RCCNZ sent a fixed-wing aircraft to search for him on Monday and has sent a mayday relay broadcast to vessels in the area for assistance if needed.
The man was one of seven DOC workers on the island, including four volunteers and three staff.
DOC manages the chain of islands, which are a nature reserve and home to five bird species unique to the islands.
The 745,000 hectares of ocean surrounding the islands is a marine reserve - volcanic Raoul Island is the biggest island at 2900ha.
NZN