Lake Matheson, Mirror lake near Fox Glacier, New Zealand

Lake Matheson is a lake near Fox Glacier with dark, mirror-smooth waters surrounded by native forest. The surface reflects the nearby mountains so clearly that you see perfect images of the peaks, especially when conditions are calm.

Lake Matheson formed about 14,000 years ago, when Fox Glacier / Te Moeka o Tuawe retreated at the end of the last glacial period. The glacier left a valley dammed by moraine and outwash gravels, plus a buried slab of ice that melted and collapsed into the lake bed. Māori travelling the coast to collect pounamu stopped here at Te Ara Kairaumati to catch longfin eels and waterbirds. European settlers named it after Murdoch Matheson, a cattle farmer in the area in the 1870s.

Māori know the lake as Te Ara Kairaumati and used it as a mahinga kai, a food-gathering place, for travellers collecting pounamu along the coast, who stopped to catch longfin eels and waterbirds. The European name honours Murdoch Matheson, a cattle farmer on the Cook River flats in the 1870s.

A walk around the lake takes roughly ninety minutes and passes through several viewing spots. Wear comfortable shoes and prepare for changing weather, as this area can be windy and rainy.

The lake has no major river inflow or outflow; it is fed by small streams and seepage through native bush. Their tannins and organic matter turn the water acidic, with pH recorded as low as 5.5, and sometimes nearly de-oxygenated. Over time the basin will fill in and become a peat bog.