HMNZS Maimai was one of eight steel New Zealand-built Castle-class ships built and commissioned by the Royal New Zealand Navy during World War II.

The vessel was ordered after the New Zealand government, facing a requirement for more minesweepers to operate in home waters, chose the Castle-class design because it was simple enough to be built with the country's limited ship construction facilities at the time.

[3] In March 1944, Maimai accidentally fired her port depth charge thrower while berthed at Picton.

[4] On 27 July 1945, she was rammed by Awatere stern-to-stern at Shelly Bay, with minor damage.

[4] In December 1945 she accompanied the aircraft carrier HMS Indefatigable on exercises in New Zealand waters.