Lake Pukaki

Where it sits. Lake Pukaki fills a glacial trough in the Mackenzie Basin of inland Canterbury, roughly 180 square kilometres of water lying almost due south of Aoraki/Mount Cook, which stands at 3,724 metres at the head of the valley and is visible down the full length of the lake on a clear day. The lake is fed by the Tasman River, which drains the Tasman and Hooker glaciers, and it is that meltwater that produces the colour: glaciers grind rock into a flour of particles fine enough to stay suspended indefinitely, and those particles scatter light back at a wavelength that reads as an improbable opaque turquoise. The effect is strongest in bright, high sun and in spring when melt is heavy. Nothing about it is enhanced, and photographs of it are routinely accused of being.

Water put to work. Pukaki is not entirely natural in its present form. It was dammed and raised in stages for the Waitaki hydroelectric scheme, with the major raising completed in the late 1970s lifting the surface by tens of metres to around 532 metres above sea level and drowning the old lakeside road and settlement. Water is now taken from the lake through the Pukaki-Ohau canal and down a chain of canals and power stations to Lake Benmore, and those canals — straight, fast, unnaturally blue lines running across the basin — are a landscape feature in their own right, lined with salmon farms and, in consequence, with anglers. The town of Twizel, at the southern end of the lake, was built from scratch in 1968 as a Ministry of Works town to house the scheme's construction workforce, was scheduled for demolition when the work finished, and survived because residents fought to keep it. It is now the service town for the whole southern end of the basin and the base for the recovery programme for kakī, the black stilt, one of the rarest wading birds in the world.

On screen. Two distinct pieces of Middle-earth were made in this basin. For The Hobbit, Lake Pukaki and the country along its shores supplied landscape material for the Long Lake and the approaches to Lake-town, with the town itself built as a set elsewhere and extended digitally — the wide water backed by high dry mountains gave exactly the right sense of a large inland lake under a mountain wall. Earlier, and more famously, the Battle of the Pelennor Fields in The Return of the King was staged on open farmland near Twizel at the southern end of the lake, under the Ben Ohau Range. The live-action charge of the Rohirrim was shot on those flats with real horses and riders, and the vast armies around them were generated with crowd-simulation software; the tussock and matagouri plain, with mountains behind and no tree or fence in shot, is the closest thing New Zealand offers to the fields before Minas Tirith. The land is private farmland and there is no marked location, though it is visible from the road.

What you actually see today. The classic view is from the lookout at the southern end where State Highway 8 crosses the outlet: a sealed car park, an information panel, a salmon shop, and the entire length of the lake running north to Aoraki. Peters Lookout, further up State Highway 80, is the better composition and less crowded. That road runs fifty-five kilometres along the western shore to Aoraki/Mount Cook Village and the Hooker Valley Track. Russell lupins flower along the shoreline in late November and early December in sheets of purple and pink; they are photogenic, invasive, and actively controlled in the braided riverbeds where they crowd out nesting habitat for wrybill and black-fronted tern.

Getting there and timing. Lake Tekapo is forty minutes east, Twizel fifteen minutes south, Christchurch about three and a half hours away and Queenstown three. The basin lies inside the Aoraki Mackenzie International Dark Sky Reserve, declared in 2012 and covering more than four thousand square kilometres, with lighting restrictions across the district; on a moonless night the Milky Way over the lake is as good as it gets in the southern hemisphere. Summer is warm and dry; winter is hard-frosted, clear and often the most rewarding, though the wind off the water is brutal in any season. Fuel and food at Twizel or Tekapo; very little in between.