Which 425 km river is the longest river in New Zealand?

New Zealand’s longest river, at 425 km, is the Waikato River.

The Waikato begins in the central North Island’s volcanic landscape, passes through the Tongariro River system and Lake Taupō, then continues north through the Waikato region. It reaches the Tasman Sea at Port Waikato, south of Auckland. The river gives its name to the surrounding region and is a major source of hydroelectric power.

A frequent mix-up is the Clutha River, or Mata-Au, which is New Zealand’s longest river on the South Island and has the country’s greatest average flow. The Whanganui is also prominent, but at about 290 km it is shorter. The Rangitīkei is shorter again, at roughly 241 km.

The Waikato’s present course was shaped by major volcanic events and a dramatic change in Lake Taupō’s outlet after the Oruanui eruption about 26,500 years ago. Its name comes from Māori, commonly interpreted as referring to flowing water.