Lake Hauroko is located in a mountain valley in Fiordland National Park in the South Island of New Zealand. The long S-shaped lake is 30 kilometres in length and covers an area of 63 km². The surface is at an altitude of 150m above sea level, and the lake is 462m deep. It is New Zealand's deepest lake.
One of the country's southernmost lakes, it is 35 kilometres northwest of Tuatapere, between the similarly-sized lakes Monowai and Poteriteri. It drains via the 20 kilometre-long Wairaurahiri River into Foveaux Strait 10 kilometres to the west of Te Waewae Bay. The name Hauroko is of Māori origin and translates into English as "sounding wind".