A Defence Force bomb squad was travelling to the West Coast of the South Island on Thursday to assess what is believed to be a World War I sea mine.
The object washed up on the beach at Kahurangi Point, north of Karamea, where it was found by a local man last week
Defence Force officials believe it could be a mine laid down by a German raider operating off the coast of New Zealand in 1917.
Police, Department of Conservation staff and Defence officials will be flown to the beach by helicopter as it is which is inaccessible by vehicle.