Lake Mapourika is a quiet, dark-water lake about 10 km north of Franz Josef on State Highway 6. It is the largest lake in Westland Tai Poutini National Park, sitting in an old glacial valley with rainforest rising directly from its shores. The water is tannin-stained and very still, which makes it the best mirror lake on the West Coast — on calm mornings the reflections of the Southern Alps are unbroken.
There is a small picnic area and boat ramp at the southern end. Several local operators run kayak tours on the lake; in summer evenings these are a fine way to see white herons and (with luck) kiwi calling from the shore. The lake is also a stop on the way to or from Okarito for those continuing north.