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 40 kilometres in length and covers an area of 63 km². The surface is at an altitude of 150 metres above sea level, and the lake is 463 metres 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 small island on the lake is the focus of several local myths, particularly one among some P?keh? who consider the island cursed by M?ori magic. Local M?ori find this funny and/or ridiculous. Really, it is a case of rural legend in action.