Lake Poteriteri is the southernmost of the large lakes in Fiordland National Park in New Zealand's South Island. Only Lakes Hakapoua and Innes lie further south on the southern of New Zealand's two main islands. It is located 40 kilometres to the west of the town of Tuatapere.Lying in a steep-sided mountain valley, Poteriteri runs roughly north-south for a distance of 28 kilometres, with an average width of under two kilometres. It covers an area of 43 km².
The outflow of Poteriteri is the Waitutu River, a short eight kilometre river which flows into the western end of Foveaux Strait.Access to the lake is via helicopter, a rough deer trail from Slaughter Burn or Harry's Track, a marked route from the outlet of Lake Hauroko.