Dau Atem, 22, originally from Sudan, walked out on friends after a night-time disagreement on Saturday, November 1.
The group of friends had been staying at a bach for the weekend.
The alarm was raised with police the following day, and searches began, including inquiries in Palmerston North based on the possibility he may have tried to hitch-hike home.
The Lowe Corporation Rescue Helicopter also covered about 10km of coastline about 500m out to sea from Mangakuri to Blackhead Beach, and the road in and out of the Shoal Bay settlement, but all search efforts for Mr Atem have proved fruitless.
Mr Atem had been studying sport and exercise at Massey University and previously had gone to high school in Wellington.