According to the NZ Herald
the Department of Conservation (DoC) volunteer, who arrived on the island in October 2011 for a six-month tour of duty, went missing at 6am on Monday, 2 January.
The volunteer's vehicle and gear were found close to where he was carrying out water temperature readings at 6am.
A search has been conducted, but fears are growing
for the missing volunteer as extensive ground and air searches failed to find the man.
DoC spokesman Tim Brandenburg, told the NZ Herald
He was down at Fishing Rock taking sea temperature readings. The vehicle that he used to go down there was at Fishing Rock, the temperature thermometer was in the water, and so we think that he had begun the task and that appears to be the mostly likely scenario - that he was swept or fell into the water somehow.
Raoul is a small island in the middle of a very big sea, so the sea conditions are often quite rough and there often isn't any natural harbour or shelter really.
According to DoC spokeswoman, Liz Maire, the missing man was one of four volunteers helping Doc staff monitor seismic and volcanic activity and conduct conservation work such as eradicating weeds to protect the more than 100 plants which are native to remote 250km-long Kermadec chain of islands
, of which Raoul is the largest, and a tightly controlled nature reserve.
The man is not the first environmental worker to disappear the island. The NZ Herald reports that 33-year-old Mark Kearney, a DoC worker on the island, disappeared during a volcanic explosion at Green Lake in 2006.
He is believed to have died when a crater lake erupted as he was checking its water temperature. His five colleagues were rescued by helicopter.
The search continues
to the east and north of Fishing Rock - areas where the 2-meter swells might have washed the missing man.