Lake Arapuni is one of several artificial lakes formed as part of a hydroelectricity scheme on the Waikato River in the North Island of New Zealand. It is 65 km (40 mi) southeast of Hamilton, to the north of Mangakino.

Lake Arapuni
1928 photograph of the dam under construction
Lake Arapuni
Location	North Island
Coordinates	38°8′10″S 175°38′10″E / 38.13611°S 175.63611°E / -38.13611; 175.63611
Type	hydroelectric reservoir
Primary inflows	Waikato River
Primary outflows	Waikato River
Basin countries	New Zealand
Surface area	9 km2 (3.5 sq mi)
Residence time	1 week
Settlements	Arapuni

The dam, at the small settlement of Arapuni at the lake's northern end, was the first constructed on the Waikato, and was commissioned in 1929.^[1] The lake occupies an area of 9.4 km² (3.6 sq mi).^[1]