'NA' (iv) was New Zealand’s final minesweeping operation to clear the German minefield laid in June 1940 in the approaches to the Hauraki Gulf (1/8 March 1945).

The total number of mines accounted for at the end of September 1941 had been 133, and since then others had drifted ashore or been sunk by ships at sea. After nearly five years of buffeting and corrosion it was probable that the rest had either sunk or drifted far away in the Pacific. Nevertheless, the area had to be thoroughly swept to make it completely safe for shipping. The New Zealand minesweepers Sanda, Scarba, Killegray and Inchkeith of the 7^th Minesweeper Trawler Group, with Waipu, Wakakura, Kaiwaka and Coastguard as dan-layers, spent eight days sweeping the Cradock Channel area off the north-western end of Great Barrier Island, but found no mines.